329:
capacity to withstand the heat of an arc. Where very low resistance is required, or low thermally-induced voltages are desired, gold-plated contacts may be used, along with palladium and other non-oxidizing, semi-precious metals. Silver or silver-plated contacts are used for signal switching. Mercury-wetted relays make and break circuits using a thin, self-renewing film of liquid mercury. For higher-power relays switching many amperes, such as motor circuit contactors, contacts are made with a mixtures of silver and cadmium oxide, providing low contact resistance and high resistance to the heat of arcing. Contacts used in circuits carrying scores or hundreds of amperes may include additional structures for heat dissipation and management of the arc produced when interrupting the circuit. Some relays have field-replaceable contacts, such as certain machine tool relays; these may be replaced when worn out, or changed between normally open and normally closed state, to allow for changes in the controlled circuit.
639:
contacts closed and others still slightly open, due to mechanical tolerances. Similarly, a relay with several normally closed (NC) contacts may stick to the unenergized position, so that when energized, the circuit through one set of contacts is broken, with a marginal gap, while the other remains closed. By introducing both NO and NC contacts, or more commonly, changeover contacts, on the same relay, it then becomes possible to guarantee that if any NC contact is closed, all NO contacts are open, and conversely, if any NO contact is closed, all NC contacts are open. It is not possible to reliably ensure that any particular contact is closed, except by potentially intrusive and safety-degrading sensing of its circuit conditions, however in safety systems it is usually the NO state that is most important, and as explained above, this is reliably verifiable by detecting the closure of a contact of opposite sense.
38:
830:
652:
1090:
slightly longer (up to a minute) delay, a dashpot is used. A dashpot is a piston filled with fluid that is allowed to escape slowly; both air-filled and oil-filled dashpots are used. The time period can be varied by increasing or decreasing the flow rate. For longer time periods, a mechanical clockwork timer is installed. Relays may be arranged for a fixed timing period, or may be field-adjustable, or remotely set from a control panel. Modern microprocessor-based timing relays provide precision timing over a great range.
186:
845:. Mercury reduces the contact resistance and mitigates the associated voltage drop. Surface contamination may result in poor conductivity for low-current signals. For high-speed applications, the mercury eliminates contact bounce, and provides virtually instantaneous circuit closure. Mercury wetted relays are position-sensitive and must be mounted according to the manufacturer's specifications. Because of the toxicity and expense of liquid mercury, these relays have increasingly fallen into disuse.
198:
1529:, and other compounds. Over time, the arc energy slowly destroys the contact metal, causing some material to escape into the air as fine particulate matter. This action causes the material in the contacts to degrade and coordination, resulting in device failure. This contact degradation drastically limits the overall life of a relay to a range of about 10,000 to 100,000 operations, a level far below the mechanical life of the device, which can be in excess of 20 million operations.
242:
and vice versa if the contacts were open. When the current to the coil is switched off, the armature is returned by a force, approximately half as strong as the magnetic force, to its relaxed position. Usually this force is provided by a spring, but gravity is also used commonly in industrial motor starters. Most relays are manufactured to operate quickly. In a low-voltage application this reduces noise; in a high voltage or current application it reduces
46:
1030:
1182:. Relays can perform the basic operations of Boolean combinatorial logic. For example, the Boolean AND function is realised by connecting normally open relay contacts in series, the OR function by connecting normally open contacts in parallel. Inversion of a logical input can be done with a normally closed contact. Relays were used for control of automated systems for machine tools and production lines. The
1019:
679:, maintains either contact position indefinitely without power applied to the coil. The advantage is that one coil consumes power only for an instant while the relay is being switched, and the relay contacts retain this setting across a power outage. A latching relay allows remote control of building lighting without the hum that may be produced from a continuously (AC) energized coil.
338:
325:(AC), some method is used to split the flux into two out-of-phase components which add together, increasing the minimum pull on the armature during the AC cycle. Typically this is done with a small copper "shading ring" crimped around a portion of the core that creates the delayed, out-of-phase component, which holds the contacts during the zero crossings of the control voltage.
540:
1291:
2330:
178:
1253:
936:
54:
1120:
1102:
In other words, the direction of the contact's motion (either to close or to open) is identical to a regular NO contact, but there is a delay in closing direction. Because the delay occurs in the direction of coil energization, this type of contact is alternatively known as a normally open, on-delay.
1089:
Timing relays are arranged for an intentional delay in operating their contacts. A very short (a fraction of a second) delay would use a copper disk between the armature and moving blade assembly. Current flowing in the disk maintains a magnetic field for a short time, lengthening release time. For a
890:
This thermal protection operates relatively slowly allowing the motor to draw higher starting currents before the protection relay will trip. Where the overload relay is exposed to the same ambient temperature as the motor, a useful though crude compensation for motor ambient temperature is provided.
642:
Force-guided contact relays are made with different main contact sets, either NO, NC or changeover, and one or more auxiliary contact sets, often of reduced current or voltage rating, used for the monitoring system. Contacts may be all NO, all NC, changeover, or a mixture of these, for the monitoring
630:
A force-guided contacts relay has relay contacts that are mechanically linked together, so that when the relay coil is energized or de-energized, all of the linked contacts move together. If one set of contacts in the relay becomes immobilized, no other contact of the same relay will be able to move.
361:
by energizing the coil. Normally open (NO) contacts connect the circuit when the relay is activated; the circuit is disconnected when the relay is inactive. Normally closed (NC) contacts disconnect the circuit when the relay is activated; the circuit is connected when the relay is inactive. All of
317:
load, there may be a similar problem of surge currents around the relay output contacts. In this case a snubber circuit (a capacitor and resistor in series) across the contacts may absorb the surge. Suitably rated capacitors and the associated resistor are sold as a single packaged component for this
241:
that activates the armature, and the consequent movement of the movable contact(s) either makes or breaks (depending upon construction) a connection with a fixed contact. If the set of contacts was closed when the relay was de-energized, then the movement opens the contacts and breaks the connection,
221:
so that when the relay is de-energized there is an air gap in the magnetic circuit. In this condition, one of the two sets of contacts in the relay pictured is closed, and the other set is open. Other relays may have more or fewer sets of contacts depending on their function. The relay in the picture
1694:
1101:
First, we have the normally open, timed-closed (NOTC) contact. This type of contact is normally open when the coil is unpowered (de-energized). The contact is closed by the application of power to the relay coil, but only after the coil has been continuously powered for the specified amount of time.
328:
Contact materials for relays vary by application. Materials with low contact resistance may be oxidized by the air, or may tend to "stick" instead of cleanly parting when opening. Contact material may be optimized for low electrical resistance, high strength to withstand repeated operations, or high
795:
A relay allows circuits to be switched by electrical equipment: for example, a timer circuit with a relay could switch power at a preset time. For many years relays were the standard method of controlling industrial electronic systems. A number of relays could be used together to carry out complex
1093:
Some relays are constructed with a kind of "shock absorber" mechanism attached to the armature, which prevents immediate, full motion when the coil is either energized or de-energized. This addition gives the relay the property of time-delay actuation. Time-delay relays can be constructed to delay
856:
of the contacts and wiring. It was quite common, before restrictions on the use of mercury, to use a mercury-wetted relay in the laboratory as a convenient means of generating fast rise time pulses, however although the rise time may be picoseconds, the exact timing of the event is, like all other
638:
Force-guided contacts by themselves can not guarantee that all contacts are in the same state, however, they do guarantee, subject to no gross mechanical fault, that no contacts are in opposite states. Otherwise, a relay with several normally open (NO) contacts may stick when energized, with some
634:
These safety relays have to follow design rules and manufacturing rules that are defined in one main machinery standard EN 50205 : Relays with forcibly guided (mechanically linked) contacts. These rules for the safety design are the one defined in type B standards such as EN 13849-2 as Basic
1135:
lines, whereas the weak signal received at an intermediate station could control a contact, regenerating the signal for further transmission. High-voltage or high-current devices can be controlled with small, low voltage wiring and pilots switches. Operators can be isolated from the high voltage
894:
The other common overload protection system uses an electromagnet coil in series with the motor circuit that directly operates contacts. This is similar to a control relay but requires a rather high fault current to operate the contacts. To prevent short over current spikes from causing nuisance
1275:
relay contacts are often used on both the positive and negative side of a circuit, so that two false feeds are needed to cause a false signal. Not all relay circuits can be proved so there is reliance on construction features such as carbon to silver contacts to resist lightning induced contact
970:
Reed relays can switch faster than larger relays and require very little power from the control circuit. However, they have relatively low switching current and voltage ratings. Though rare, the reeds can become magnetized over time, which makes them stick "on", even when no current is present;
134:
Latching relays require only a single pulse of control power to operate the switch persistently. Another pulse applied to a second set of control terminals, or a pulse with opposite polarity, resets the switch, while repeated pulses of the same kind have no effects. Magnetic latching relays are
1516:
circuit. The inrush current of tungsten filament incandescent lamps is typically ten times the normal operating current. Thus, relays intended for tungsten loads may use special contact composition, or the relay may have lower contact ratings for tungsten loads than for purely resistive loads.
682:
In one mechanism, two opposing coils with an over-center spring or permanent magnet hold the contacts in position after the coil is de-energized. A pulse to one coil turns the relay on, and a pulse to the opposite coil turns the relay off. This type is widely used where control is from simple
694:
core that retains the contacts in the operated position by the remanent magnetism in the core. This type requires a current pulse of opposite polarity to release the contacts. A variation uses a permanent magnet that produces part of the force required to close the contact; the coil supplies
902:
Electronic overload protection relays measure motor current and can estimate motor winding temperature using a "thermal model" of the motor armature system that can be set to provide more accurate motor protection. Some motor protection relays include temperature detector inputs for direct
820:
is a relay that uses mercury as the switching element. They are used where contact erosion would be a problem for conventional relay contacts. Owing to environmental considerations about significant amount of mercury used and modern alternatives, they are now comparatively uncommon.
584:
Where radio transmitters and receivers share one antenna, often a coaxial relay is used as a TR (transmit-receive) relay, which switches the antenna from the receiver to the transmitter. This protects the receiver from the high power of the transmitter. Such relays are often used in
1110:
A vacuum relay is a sensitive relay having its contacts mounted in an evacuated glass housing, to permit handling radio-frequency voltages as high as 20,000 volts without flashover between contacts even though contact spacing is as low as a few hundredths of an inch when open.
1520:
An electrical arc across relay contacts can be very hot β thousands of degrees
Fahrenheit β causing the metal on the contact surfaces to melt, pool, and migrate with the current. The extremely high temperature of the arc splits the surrounding gas molecules, creating
1097:
Time-delay relay contacts must be specified not only as either normally open or normally closed, but whether the delay operates in the direction of closing or in the direction of opening. The following is a description of the four basic types of time-delay relay contacts.
860:
The same coalescence process causes another effect, which is a nuisance in some applications. The contact resistance is not stable immediately after contact closure, and drifts, mostly downwards, for several seconds after closure, the change perhaps being 0.5 ohm.
1400:
Size β smaller relays often resist mechanical vibration and shock better than larger relays, because of the lower inertia of the moving parts and the higher natural frequencies of smaller parts. Larger relays often handle higher voltage and current than smaller
631:
The function of force-guided contacts is to enable the safety circuit to check the status of the relay. Force-guided contacts are also known as "positive-guided contacts", "captive contacts", "locked contacts", "mechanically linked contacts", or "safety relays".
119:. Relays with calibrated operating characteristics and sometimes multiple operating coils are used to protect electrical circuits from overload or faults; in modern electric power systems these functions are performed by digital instruments still called
250:
1870:
Section 1.6, Engineers' Relay
Handbook, 5th ed, Relay and Switch Industry Association, Arlington, VA; 3rd ed, National Association of Relay Manufacturers, Elkhart Ind., 1980; 2nd Ed. Hayden, New York, 1966; large parts of the 5th edition are on line
301:
were easily destroyed by this surge. Some automotive relays include a diode inside the relay case. Resistors, while more durable than diodes, are less efficient at eliminating voltage spikes generated by relays and therefore not as commonly used.
1323:
Operating lifetime, useful life β the number of times the relay can be expected to operate reliably. There is both a mechanical life and a contact life. The contact life is affected by the type of load switched. Breaking load current causes
784:, transfer machines, and other sequential control. They are characterized by a large number of contacts (sometimes extendable in the field) which are easily converted from normally open to normally closed status, easily replaceable coils, and a
1267:
relays are large considering the mostly small voltages (less than 120 V) and currents (perhaps 100 mA) that they switch. Contacts are widely spaced to prevent flashovers and short circuits over a lifetime that may exceed fifty years.
882:
protection to prevent damage from over-loading the motor, or to protect against short circuits in connecting cables or internal faults in the motor windings. The overload sensing devices are a form of heat operated relay where a coil heats a
869:
Multi-voltage relays are devices designed to work for wide voltage ranges such as 24 to 240 VAC and VDC and wide frequency ranges such as 0 to 300 Hz. They are indicated for use in installations that do not have stable supply voltages.
1140:
can drive relays to control electrical loads beyond their direct drive capability. In an automobile, a starter relay allows the high current of the cranking motor to be controlled with small wiring and contacts in the ignition key.
589:
which combine transmitter and receiver in one unit. The relay contacts are designed not to reflect any radio frequency power back toward the source, and to provide very high isolation between receiver and transmitter terminals. The
1239:
For protection of electrical apparatus and transmission lines, electromechanical relays with accurate operating characteristics were used to detect overload, short-circuits, and other faults. While many such relays remain in use,
1470:
Switching while "wet" (under load) causes undesired arcing between the contacts, eventually leading to contacts that weld shut or contacts that fail due to a buildup of surface damage caused by the destructive arc energy.
1493:
causes significant degradation of the contacts, which suffer significant and visible damage. Every time the relay contacts open or close under load, an electrical arc can occur between the contacts of the relay, either a
217:, and one or more sets of contacts (there are two contacts in the relay pictured). The armature is hinged to the yoke and mechanically linked to one or more sets of moving contacts. The armature is held in place by a
706:
has a ratchet mechanism that holds the contacts closed after the coil is momentarily energized. A second impulse, in the same or a separate coil, releases the contacts. This type may be found in certain cars, for
1152:
telephone exchanges made extensive use of relays in ancillary control circuits. The Relay
Automatic Telephone Company also manufactured telephone exchanges based solely on relay switching techniques designed by
1216:
Relays are much more resistant than semiconductors to nuclear radiation, so they are widely used in safety-critical logic, such as the control panels of radioactive waste-handling machinery. Electromechanical
502:
are among applicable standards for relay terminal numbering; a typical EN 50005-compliant SPDT relay's terminals would be numbered 11, 12, 14, A1 and A2 for the C, NC, NO, and coil connections, respectively.
989:
are devices which generally implement protection functions. In the event of a hazard, the task of such a safety function is to use appropriate measures to reduce the existing risk to an acceptable level.
1313:
Contact sequence β "make before break" or "break before make". For example, the old style telephone exchanges required make-before-break so that the connection did not get dropped while dialing the
428:β Double-Pole Single-Throw relays are equivalent to a pair of SPST switches or relays actuated by a single coil. Including two for the coil, such a relay has a total of six terminals. The poles may be
1916:
EN 50005:1976 "Specification for low voltage switchgear and controlgear for industrial use. Terminal marking and distinctive number. General rules." (1976). In the UK published by BSI as BS 5472:1977.
162:
for his telegraph, which is now called a relay. The mechanism described acted as a digital amplifier, repeating the telegraph signal, and thus allowing signals to be propagated as far as desired.
88:
Relays are used where it is necessary to control a circuit by an independent low-power signal, or where several circuits must be controlled by one signal. Relays were first used in long-distance
253:
257:
256:
252:
251:
1445:
larger than the steady-state current exists. When the circuit is broken, the current cannot change instantaneously, which creates a potentially damaging arc across the separating contacts.
258:
422:
contacts. That is, a common terminal connects to either of two others, never connecting to both at the same time. Including two for the coil, such a relay has a total of five terminals.
81:. It consists of a set of input terminals for a single or multiple control signals, and a set of operating contact terminals. The switch may have any number of contacts in multiple
887:, or where a solder pot melts, to operate auxiliary contacts. These auxiliary contacts are in series with the motor's contactor coil, so they turn off the motor when it overheats.
1002:, and lighting loads. There are no moving parts to wear out and there is no contact bounce due to vibration. They are activated by AC control signals or DC control signals from
998:
A solid-state contactor is a heavy-duty solid state relay, including the necessary heat sink, used where frequent on-off cycles are required, such as with electric heaters, small
643:
contacts, so that the safety system designer can select the correct configuration for the particular application. Safety relays are used as part of an engineered safety system.
1722:
1414:
There are many considerations involved in the correct selection of a control relay for a particular application, including factors such as speed of operation, sensitivity, and
1178:
788:
that allows compactly installing many relays in a control panel. Although such relays once were the backbone of automation in such industries as automobile assembly, the
255:
695:
sufficient force to move the contact open or closed by aiding or opposing the field of the permanent magnet. A polarity controlled relay needs changeover switches or an
1700:
1334:
Coil current β Minimum current required for reliable operation and minimum holding current, as well as effects of power dissipation on coil temperature at various
614:
and lighting loads. Continuous current ratings for common contactors range from 10 amps to several hundred amps. High-current contacts are made with alloys containing
222:
also has a wire connecting the armature to the yoke. This ensures continuity of the circuit between the moving contacts on the armature, and the circuit track on the
1271:
Since rail signal circuits must be highly reliable, special techniques are used to detect and prevent failures in the relay system. To protect against false feeds,
1692:, Morse, Samuel E.B., "Improvement in the Mode of Communicating Information by Signals by the Application of Electromagnetism", published June 20, 1840
1482:
and certain other high-reliability designs, the reed switches are always switched "dry" (without load) to avoid that problem, leading to much longer contact life.
759:. Such an electrically latching relay requires continuous power to maintain state, unlike magnetically latching relays or mechanically ratcheting relays. While
37:
1355:
Assembly β Some relays feature a sticker that keeps the enclosure sealed to allow PCB post soldering cleaning, which is removed once assembly is complete.
1448:
Consequently, for relays used to control inductive loads, we must specify the maximum current that may flow through the relay contacts when it actuates, the
1320:
Contact voltage rating β typical control relays rated 300 VAC or 600 VAC, automotive types to 50 VDC, special high-voltage relays to about 15,000 V
852:, and the current rise time through the contacts is generally considered to be a few picoseconds. However, in a practical circuit it may be limited by the
919:
A polarized relay places the armature between the poles of a permanent magnet to increase sensitivity. Polarized relays were used in middle 20th
Century
699:
drive circuit to control it. The relay may be less expensive than other types, but this is partly offset by the increased costs in the external circuit.
92:
circuits as signal repeaters: they refresh the signal coming in from one circuit by transmitting it on another circuit. Relays were used extensively in
1875:
1352:
Operating environment β minimum and maximum operating temperature and other environmental considerations, such as effects of humidity and salt
1646:
Scientific
American Inventions and Discoveries: All the Milestones in Ingenuity--From the Discovery of Fire to the Invention of the Microwave Oven
1342:
1317:
Contact current rating β small relays switch a few amperes, large contactors are rated for up to 3000 amperes, alternating or direct current
386:
contact. These have two terminals which can be connected or disconnected. Including two for the coil, such a relay has four terminals in total.
254:
1512:
arc is more energetic and thus more destructive, in particular with inductive loads, but this can be mitigated by bridging the contacts with a
1475:
460:
contacts. These are equivalent to two SPDT switches or relays actuated by a single coil. Such a relay has eight terminals, including the coil
2036:
1983:
1956:
1299:
2107:
1295:
755:βthey store bits in ordinary wire-spring relays or reed relays by feeding an output wire back as an input, resulting in a feedback loop or
2238:
800:). The principle of relay logic is based on relays which energize and de-energize associated contacts. Relay logic is the predecessor of
1619:
2355:
1081:
consists of electronic circuitry to emulate all those characteristics which are achieved by moving parts in an electro-magnetic relay.
2060:
1855:
1654:
1603:
214:
1127:
Relays are used wherever it is necessary to control a high power or high voltage circuit with a low power circuit, especially when
2370:
1364:"Dry" contacts β when switching very low level signals, special contact materials may be needed such as gold-plated contacts
1057:
or other solid-state switching device, activated by the control signal, to switch the controlled load, instead of a solenoid. An
978:
Sealed contacts with mercury-wetted contacts have longer operating lives and less contact chatter than any other kind of relay.
365:
The
National Association of Relay Manufacturers and its successor, the Relay and Switch Industry Association define 23 distinct
2077:
1433:
As with any switch, the contact current (unrelated to the coil current) must not exceed a given value to avoid damage. In high-
1358:
Mounting β sockets, plug board, rail mount, panel mount, through-panel mount, enclosure for mounting on walls or equipment
306:
2121:
1736:
1689:
1331:
Coil voltage β machine-tool relays usually 24 VDC, 120 or 250 VAC, relays for switchgear may have 125 V or 250 VDC coils,
62:
57:
Electromechanical relay schematic showing a control coil, four pairs of normally open and one pair of normally closed contacts
1934:
1833:
1644:
848:
The high speed of switching action of the mercury-wetted relay is a notable advantage. The mercury globules on each contact
1593:
1003:
805:
789:
726:
2385:
2380:
829:
2350:
1558:
1183:
1007:
298:
2186:
1328:
between the contacts, eventually leading to contacts that weld shut or contacts that fail due to erosion by the arc.
2375:
2360:
1282:
are also used in some instances with railway signalling, especially where only a single contact is to be switched.
492:) designator for the pole count may be replaced with a number, indicating multiple contacts connected to a single
2303:
1456:. The make rating may be several times larger than the continuous rating, which is larger than the break rating.
1042:
1022:
1168:
The use of relays for the logical control of complex switching systems like telephone exchanges was studied by
967:
material that makes them move under the influence of the field of the enclosing solenoid or an external magnet.
1241:
651:
591:
107:
to close or open the contacts, but relays using other operating principles have also been invented, such as in
1896:
1306:
Selection of an appropriate relay for a particular application requires evaluation of many different factors:
2267:
309:
A small cradle relay often used in electronics. The "cradle" term refers to the shape of the relay's armature
1049:
relay but does not have any moving components, increasing long-term reliability. A solid-state relay uses a
185:
135:
useful in applications when interrupted power should not affect the circuits that the relay is controlling.
1872:
1213:
used relays for logic and working registers. However, electronic devices proved faster and easier to use.
939:(from top) Single-pole reed switch, four-pole reed switch and single-pole reed relay. Scale in centimeters
908:
31:
1701:"Patent US1647 - IMPROVEMENT IN THE MODE OF COMMUNICATING INFORMATION BY SIGNALS BY THE - Google Patents"
555:
549:
1346:
899:. The thermal and magnetic overload detections are typically used together in a motor protection relay.
849:
223:
622:
is still a good conductor. Contactors with overload protection devices are often used to start motors.
197:
1062:
857:
types of relay, subject to considerable jitter, possibly milliseconds, due to mechanical variations.
761:
314:
152:
89:
1754:
1194:
752:
733:
354:
322:
210:
45:
1486:
1264:
1132:
1128:
756:
719:
366:
93:
82:
1430:
which are actuated by low currents and switch fast are suitable for controlling small currents.
2242:
1154:
635:
safety principles and Well-tried safety principles for machinery that applies to all machines.
496:. For example, 4PDT indicates a four-pole double-throw relay that has 12 switching terminals.
2151:"Recent Developments in Bell System Relays β Particularly Sealed Contact and Miniature Relays"
2056:
2032:
1979:
1952:
1930:
1851:
1829:
1716:
1650:
1623:
1599:
1573:
1388:
1046:
1038:
842:
772:, which in turn was replaced by a series of ever faster and ever smaller memory technologies.
769:
595:
469:
463:
456:
436:
430:
410:
394:
378:
349:, the terminology applied to switches is also applied to relays; a relay switches one or more
108:
100:
2203:
1973:
2217:
2162:
1272:
1234:
1218:
1066:
884:
711:
dipping and other functions where alternating operation on each switch actuation is needed.
281:
is often placed across the coil to dissipate the energy from the collapsing magnetic field (
234:
121:
2365:
1879:
1568:
1538:
1526:
1479:
1465:
1370:
Coil protection β suppress the surge voltage produced when switching the coil current
1341:
Package/enclosure β open, touch-safe, double-voltage for isolation between circuits,
1222:
1202:
1198:
1173:
1149:
1145:
920:
715:
218:
1780:
1441:, other issues must be addressed. When an inductance is connected to a power source, an
1221:
are used to detect overload and other faults on electrical lines by opening and closing
2166:
1672:
1563:
1543:
1442:
1438:
1169:
1137:
999:
838:
611:
267:
238:
151:
is often cited to have invented a relay in 1835 in order to improve his version of the
1029:
2344:
1802:
1553:
1279:
817:
290:
286:
271:
206:
190:
112:
104:
1999:
792:(PLC) mostly displaced the machine tool relay from sequential control applications.
1801:
Riba, J.R.; Espinosa, A.G.; CusidΓ³, J.; Ortega, J.A.; Romeral, L. (November 2008).
1781:"Art & Science of Protective Relaying, Chapter 2, GE Consumer & Electrical"
1490:
1410:
Stray magnetic linkage between coils of adjacent relays on a printed circuit board.
1380:
1257:
1078:
986:
975:
the switch with respect to the solenoid's magnetic field can resolve this problem.
904:
801:
781:
683:
switches or single-ended outputs of a control system, and such relays are found in
619:
159:
148:
127:
116:
1310:
Number and type of contacts β normally open, normally closed, (double-throw)
369:
found in relays and switches. Of these, the following are commonly encountered:
341:
Circuit symbols of relays (C denotes the common terminal in SPDT and DPDT types.)
1548:
1423:
1419:
1187:
1058:
1018:
948:
879:
797:
745:
586:
718:
is a specialized kind of multi-way latching relay designed for early automatic
293:
circuit components. Such diodes were not widely used before the application of
1434:
1427:
1415:
1404:
Accessories such as timers, auxiliary contacts, pilot lamps, and test buttons.
1335:
972:
944:
924:
853:
560:
294:
2334:
402:
contact. As with an SPST-NO relay, such a relay has four terminals in total.
1804:
Design of
Shading Coils for Minimizing the Contact Bouncing of AC Contactors
1384:
1162:
1050:
960:
956:
765:
are often realized with relays they can also be implemented by other means.
691:
607:
506:
144:
337:
205:
A simple electromagnetic relay consists of a coil of wire wrapped around a
2329:
2150:
1595:
Icons of
Invention: The Makers of the Modern World from Gutenberg to Gates
1290:
708:
696:
684:
493:
282:
278:
74:
768:
In computer memories, latching relays and other relays were replaced by
177:
169:
appears in the context of electromagnetic operations from 1860 onwards.
1513:
1392:
1252:
1210:
1206:
896:
741:
737:
275:
2289:
1294:
Several 30-contact relays in "Connector" circuits in mid-20th century
935:
780:
A machine tool relay is a type standardized for industrial control of
610:
is a heavy-duty relay with higher current ratings, used for switching
201:
Operation with flyback diode, arcing in the control circuit is avoided
17:
1504:
1010:(TTL) sources, or other microprocessor and microcontroller controls.
964:
952:
785:
615:
346:
78:
1367:
Contact protection β suppress arcing in very inductive circuits
30:
This article is about the electrical component. For other uses, see
1376:
Aerospace or radiation-resistant testing, special quality assurance
1119:
951:
enclosed in a solenoid. The switch has a set of contacts inside an
837:
A mercury-wetted reed relay is a form of reed relay that employs a
53:
2304:"Lab Note #105: Contact Life β Unsuppressed vs. Suppressed Arcing"
1522:
1289:
1251:
1118:
1054:
1028:
1017:
959:-filled glass tube that protects the contacts against atmospheric
934:
828:
650:
618:. The unavoidable arcing causes the contacts to oxidize; however,
336:
305:
304:
248:
196:
184:
176:
85:, such as make contacts, break contacts, or combinations thereof.
60:
52:
44:
36:
392:(Single-Pole Single-Throw, Normally-Closed) relays have a single
362:
the contact forms involve combinations of NO and NC connections.
65:
An automotive-style miniature relay with the dust cover taken off
1094:
armature motion on coil energization, de-energization, or both.
227:
61:
2268:"Arc Suppression to Protect Relays From Destructive Arc Energy"
2262:
2260:
1951:(Eleventh ed.). New York: McGraw Hill. p. 7-124.
376:(Single-Pole Single-Throw, Normally-Open) relays have a single
1244:
now provide equivalent and more complex protective functions.
533:
2122:"Overload relay - Principle of operation, types, connection"
1422:
to 20 ms range, relays with switching speeds as fast as 100
1045:
electronic component that provides a function similar to an
736:
often stored bits in a magnetically latching relay, such as
1158:
1157:. The first public relay based telephone exchange in the
1131:
is desirable. The first application of relays was in long
1069:) can be used to isolate control and controlled circuits.
158:
However, an official patent was not issued until 1840 to
751:
Some early computers used ordinary relays as a kind of
408:(Single-Pole Double-Throw) relays have a single set of
2187:"Safety Compendium, Chapter 4 Safe control technology"
2000:"Contactor or Motor Starter β What is the Difference?"
509:
defines contact numbers in relays for automotive use:
297:
as relay drivers, but soon became ubiquitous as early
2078:"Working Principle of Thermal Motor Protection Relay"
1443:
input surge current or electromotor starting current
1165:
on 15 July 1922 and remained in service until 1959.
285:) at deactivation, which would otherwise generate a
143:
Electrical relays got their start in application to
1418:. Although typical control relays operate in the 5
1338:. "Sensitive" relays operate on a few milliamperes.
1179:
A Symbolic
Analysis of Relay and Switching Circuits
547:It has been suggested that this article should be
454:β Double-Pole Double-Throw relays have two sets of
96:and early computers to perform logical operations.
1671:
1649:. John Wiley & Sons. 2005-01-28. p. 311.
1361:Switching time β where high speed is required
1345:, outdoor, oil and splash resistant, washable for
895:triggering the armature movement is damped with a
193:, arcing causes degradation of the switch contacts
313:If the relay is driving a large, or especially a
1972:Rexford, Kenneth B.; Giuliani, Peter R. (2002).
1721:: CS1 maint: bot: original URL status unknown (
209:(a solenoid), an iron yoke which provides a low
1947:Croft, Terrell; Summers, Wilford, eds. (1987).
598:impedance of the system, for example, 50 ohms.
1978:(6th ed.). Cengage Learning. p. 58.
1144:Electromechanical switching systems including
1123:A DPDT AC coil relay with "ice cube" packaging
1033:25 A and 40 A solid state contactors
1620:"The electromechanical relay of Joseph Henry"
321:If the coil is designed to be energized with
8:
1755:"Understanding Relays & Wiring Diagrams"
1703:. Archived from the original on May 24, 2012
1508:arc (when closing). In many situations, the
2306:. Arc Suppression Technologies. April 2011
2022:
2020:
1302:telephone exchanges; cover removed on one.
237:is passed through the coil it generates a
115:properties for control without relying on
2144:
2142:
1387:applications are designed to function in
1260:using UK Q-style miniature plug-in relays
971:changing the orientation of the reeds or
448:should be used to resolve the ambiguity).
2102:"Coordinated Power Systems Protection".
1678:. Princeton: Princeton University Press.
841:, in which the contacts are wetted with
2104:Department of the Army Technical Manual
2055:. Schweitzer Engineering Laboratories.
2031:(3rd ed.), Elsevier, p. 262,
1585:
729:includes a specialized latching relay.
213:path for magnetic flux, a movable iron
2290:"Questions About The No. 1 ESS Switch"
1714:
1476:Number One Electronic Switching System
687:and numerous industrial applications.
1927:Passive Components for Circuit Design
1890:
1888:
1826:Passive Components for Circuit Design
1325:
243:
7:
2108:United States Department of the Army
1276:welding and to provide AC immunity.
1172:, who formalized the application of
655:Latching relay with permanent magnet
2239:"British Telecom History 1912-1968"
2218:"Relay Automatic Telephone Company"
1136:circuit. Low power devices such as
923:to detect faint pulses and correct
2167:10.1002/j.1538-7305.1964.tb04057.x
1904:Db: The Sound Engineering Magazine
1807:. Electrical Contacts. p. 130
440:(or one of each; the designations
25:
2155:The Bell System Technical Journal
2082:Electrical-Engineering-Portal.com
1452:; the continuous rating; and the
1379:Expected mechanical loads due to
49:Electromechanical relay principle
2328:
1846:Fleckenstein, Joseph E. (2017).
1622:. Georgi Dalakov. Archived from
911:sensor embedded in the winding.
538:
266:When the coil is energized with
230:, which is soldered to the PCB.
2084:. Electrical Engineering Portal
1975:Electrical control for machines
1949:American Electricians' Handbook
1897:"The Audio Engineer's Handbook"
1674:Joseph Henry: His Life and Work
1598:. ABC-CLIO. 2009. p. 153.
1373:Isolation between coil contacts
594:of the relay is matched to the
522:87a = to load (normally closed)
1004:programmable logic controllers
806:programmable logic controllers
659:A latching relay, also called
181:Simple electromechanical relay
1:
2149:Keller, A.C. (January 1964).
1155:Gotthilf Ansgarius Betulander
790:programmable logic controller
727:earth-leakage circuit breaker
155:, developed earlier in 1831.
1848:Three-Phase Electrical Power
1383: β some relays used in
1195:electro-mechanical computers
1186:is often used for designing
1025:relays have no moving parts.
804:, which is commonly used in
690:Another latching type has a
519:87 = to load (normally open)
27:Electrically-operated switch
2126:www.electricalclassroom.com
1559:Nanoelectromechanical relay
1184:Ladder programming language
1176:to relay circuit design in
1008:transistor-transistor logic
963:; the contacts are made of
833:A mercury-wetted reed relay
626:Force-guided contacts relay
2402:
2356:Electromagnetic components
1850:. CRC Press. p. 321.
1463:
1232:
553:into a new article titled
173:Basic design and operation
29:
2027:Sinclair, Ian R. (2001),
1498:arc (when opening), or a
1242:digital protective relays
874:Overload protection relay
262:Operation of a 12 A relay
1286:Selection considerations
592:characteristic impedance
472:β combination of D and B
367:electrical contact forms
103:form of a relay uses an
2371:19th-century inventions
2029:Sensors and Transducers
1895:Alexandrovich, George.
1670:Thomas Coulson (1950).
1491:electric current arcing
762:(self-)holding circuits
2288:Varney, Al L. (1991).
2204:"Optocoupler Tutorial"
2051:Zocholl, Stan (2003).
1460:Safety and reliability
1303:
1261:
1124:
1034:
1026:
940:
925:telegraphic distortion
909:resistance thermometer
834:
656:
342:
310:
263:
202:
194:
182:
66:
58:
50:
42:
32:Relay (disambiguation)
2076:Edvard (2013-03-09).
1906:. September 1968: 10.
1407:Regulatory approvals.
1347:printed circuit board
1293:
1255:
1122:
1065:(LED) coupled with a
1032:
1021:
994:Solid-state contactor
938:
878:Electric motors need
832:
654:
340:
308:
299:germanium transistors
261:
224:printed circuit board
200:
188:
180:
147:. American scientist
64:
56:
48:
40:
2337:at Wikimedia Commons
2206:. 16 September 2013.
1489:, the occurrence of
1063:light-emitting diode
865:Multi-voltage relays
825:Mercury-wetted relay
153:electrical telegraph
2386:Digital electronics
2381:American inventions
2245:on October 14, 2014
2053:AC Motor Protection
921:telephone exchanges
903:measurement from a
720:telephone exchanges
702:In another type, a
556:List of relay types
466:β make before break
323:alternating current
94:telephone exchanges
2351:1835 introductions
1878:2017-07-05 at the
1487:contact protection
1304:
1265:Railway signalling
1262:
1129:galvanic isolation
1125:
1035:
1027:
941:
835:
776:Machine tool relay
757:sequential circuit
657:
343:
311:
264:
203:
195:
189:Operation without
183:
109:solid-state relays
67:
59:
51:
43:
2376:German inventions
2361:Power engineering
2333:Media related to
2038:978-0-7506-4932-2
1985:978-0-7668-6198-5
1958:978-0-07-013932-9
1828:, Elsevier, 2000
1574:Wire spring relay
1485:Without adequate
1437:circuits such as
1248:Railway signaling
1229:Protective relays
1219:protective relays
1161:was installed in
1047:electromechanical
1039:solid-state relay
1014:Solid-state relay
770:delay-line memory
675:relay, or simply
596:transmission line
577:
576:
516:86 = relay coil +
513:85 = relay coil -
416:break before make
345:Since relays are
318:commonplace use.
259:
122:protective relays
101:electromechanical
16:(Redirected from
2393:
2332:
2316:
2315:
2313:
2311:
2300:
2294:
2293:
2285:
2279:
2278:
2276:
2274:
2264:
2255:
2254:
2252:
2250:
2241:. Archived from
2235:
2229:
2228:
2226:
2224:
2214:
2208:
2207:
2200:
2194:
2193:
2191:
2183:
2177:
2176:
2174:
2173:
2146:
2137:
2136:
2134:
2133:
2118:
2112:
2111:
2099:
2093:
2092:
2090:
2089:
2073:
2067:
2066:
2048:
2042:
2041:
2024:
2015:
2014:
2012:
2011:
1996:
1990:
1989:
1969:
1963:
1962:
1944:
1938:
1923:
1917:
1914:
1908:
1907:
1901:
1892:
1883:
1868:
1862:
1861:
1843:
1837:
1822:
1816:
1815:
1813:
1812:
1798:
1792:
1791:
1789:
1787:
1776:
1770:
1769:
1767:
1765:
1751:
1745:
1744:
1733:
1727:
1726:
1720:
1712:
1710:
1708:
1698:
1697:
1693:
1686:
1680:
1679:
1677:
1667:
1661:
1660:
1641:
1635:
1634:
1632:
1631:
1616:
1610:
1609:
1590:
1326:undesired arcing
1273:double switching
1256:Part of a relay
1235:Protective relay
1223:circuit breakers
1085:Time-delay relay
1067:photo transistor
885:bimetallic strip
572:
569:
542:
541:
534:
353:, each of whose
260:
235:electric current
99:The traditional
21:
2401:
2400:
2396:
2395:
2394:
2392:
2391:
2390:
2341:
2340:
2325:
2320:
2319:
2309:
2307:
2302:
2301:
2297:
2287:
2286:
2282:
2272:
2270:
2266:
2265:
2258:
2248:
2246:
2237:
2236:
2232:
2222:
2220:
2216:
2215:
2211:
2202:
2201:
2197:
2189:
2185:
2184:
2180:
2171:
2169:
2148:
2147:
2140:
2131:
2129:
2120:
2119:
2115:
2101:
2100:
2096:
2087:
2085:
2075:
2074:
2070:
2063:
2050:
2049:
2045:
2039:
2026:
2025:
2018:
2009:
2007:
1998:
1997:
1993:
1986:
1971:
1970:
1966:
1959:
1946:
1945:
1941:
1929:, Newnes, 2000
1924:
1920:
1915:
1911:
1899:
1894:
1893:
1886:
1880:Wayback Machine
1869:
1865:
1858:
1845:
1844:
1840:
1823:
1819:
1810:
1808:
1800:
1799:
1795:
1785:
1783:
1778:
1777:
1773:
1763:
1761:
1753:
1752:
1748:
1735:
1734:
1730:
1713:
1706:
1704:
1699:
1695:
1688:
1687:
1683:
1669:
1668:
1664:
1657:
1643:
1642:
1638:
1629:
1627:
1618:
1617:
1613:
1606:
1592:
1591:
1587:
1582:
1569:Stepping switch
1539:Analogue switch
1535:
1527:carbon monoxide
1480:crossbar switch
1468:
1466:Arc suppression
1462:
1426:are available.
1343:explosion proof
1288:
1250:
1237:
1231:
1203:Harvard Mark II
1174:Boolean algebra
1138:microprocessors
1117:
1108:
1087:
1075:
1016:
1000:electric motors
996:
984:
933:
917:
915:Polarized relay
876:
867:
827:
814:
778:
734:early computers
649:
628:
612:electric motors
604:
582:
573:
567:
564:
543:
539:
532:
335:
249:
175:
141:
35:
28:
23:
22:
15:
12:
11:
5:
2399:
2397:
2389:
2388:
2383:
2378:
2373:
2368:
2363:
2358:
2353:
2343:
2342:
2339:
2338:
2324:
2323:External links
2321:
2318:
2317:
2295:
2280:
2256:
2230:
2209:
2195:
2192:. p. 115.
2178:
2138:
2113:
2094:
2068:
2062:978-0972502610
2061:
2043:
2037:
2016:
2004:EECOOnline.com
1991:
1984:
1964:
1957:
1939:
1925:Ian Sinclair,
1918:
1909:
1884:
1863:
1857:978-1498737784
1856:
1838:
1824:Ian Sinclair,
1817:
1793:
1771:
1746:
1741:EtymOnline.com
1728:
1681:
1662:
1655:
1636:
1611:
1604:
1584:
1583:
1581:
1578:
1577:
1576:
1571:
1566:
1564:Race condition
1561:
1556:
1551:
1546:
1544:Buchholz relay
1541:
1534:
1531:
1464:Main article:
1461:
1458:
1412:
1411:
1408:
1405:
1402:
1398:
1377:
1374:
1371:
1368:
1365:
1362:
1359:
1356:
1353:
1350:
1339:
1332:
1329:
1321:
1318:
1315:
1311:
1287:
1284:
1280:Opto-isolators
1249:
1246:
1233:Main article:
1230:
1227:
1170:Claude Shannon
1116:
1113:
1107:
1104:
1086:
1083:
1074:
1071:
1015:
1012:
995:
992:
983:
980:
932:
929:
916:
913:
875:
872:
866:
863:
839:mercury switch
826:
823:
813:
810:
777:
774:
716:stepping relay
648:
647:Latching relay
645:
627:
624:
603:
600:
581:
578:
575:
574:
568:September 2021
546:
544:
537:
531:
528:
527:
526:
525:30 = battery +
523:
520:
517:
514:
474:
473:
467:
461:
449:
423:
403:
387:
334:
331:
268:direct current
239:magnetic field
226:(PCB) via the
207:soft iron core
174:
171:
140:
137:
26:
24:
14:
13:
10:
9:
6:
4:
3:
2:
2398:
2387:
2384:
2382:
2379:
2377:
2374:
2372:
2369:
2367:
2364:
2362:
2359:
2357:
2354:
2352:
2349:
2348:
2346:
2336:
2331:
2327:
2326:
2322:
2305:
2299:
2296:
2291:
2284:
2281:
2269:
2263:
2261:
2257:
2244:
2240:
2234:
2231:
2219:
2213:
2210:
2205:
2199:
2196:
2188:
2182:
2179:
2168:
2164:
2160:
2156:
2152:
2145:
2143:
2139:
2127:
2123:
2117:
2114:
2109:
2105:
2098:
2095:
2083:
2079:
2072:
2069:
2064:
2058:
2054:
2047:
2044:
2040:
2034:
2030:
2023:
2021:
2017:
2005:
2001:
1995:
1992:
1987:
1981:
1977:
1976:
1968:
1965:
1960:
1954:
1950:
1943:
1940:
1936:
1932:
1928:
1922:
1919:
1913:
1910:
1905:
1898:
1891:
1889:
1885:
1881:
1877:
1874:
1867:
1864:
1859:
1853:
1849:
1842:
1839:
1836:, pp. 161β164
1835:
1831:
1827:
1821:
1818:
1806:
1805:
1797:
1794:
1782:
1779:Mason, C. R.
1775:
1772:
1760:
1756:
1750:
1747:
1742:
1738:
1732:
1729:
1724:
1718:
1702:
1691:
1685:
1682:
1676:
1675:
1666:
1663:
1658:
1656:9780471660248
1652:
1648:
1647:
1640:
1637:
1626:on 2012-06-18
1625:
1621:
1615:
1612:
1607:
1605:9780313347436
1601:
1597:
1596:
1589:
1586:
1579:
1575:
1572:
1570:
1567:
1565:
1562:
1560:
1557:
1555:
1554:Flyback diode
1552:
1550:
1547:
1545:
1542:
1540:
1537:
1536:
1532:
1530:
1528:
1524:
1518:
1515:
1511:
1507:
1506:
1501:
1497:
1492:
1488:
1483:
1481:
1477:
1472:
1467:
1459:
1457:
1455:
1451:
1446:
1444:
1440:
1436:
1431:
1429:
1425:
1421:
1417:
1409:
1406:
1403:
1399:
1396:
1395:
1390:
1386:
1382:
1378:
1375:
1372:
1369:
1366:
1363:
1360:
1357:
1354:
1351:
1348:
1344:
1340:
1337:
1333:
1330:
1327:
1322:
1319:
1316:
1312:
1309:
1308:
1307:
1301:
1297:
1292:
1285:
1283:
1281:
1277:
1274:
1269:
1266:
1259:
1254:
1247:
1245:
1243:
1236:
1228:
1226:
1224:
1220:
1214:
1212:
1208:
1204:
1200:
1196:
1191:
1189:
1185:
1181:
1180:
1175:
1171:
1166:
1164:
1160:
1156:
1151:
1147:
1142:
1139:
1134:
1130:
1121:
1114:
1112:
1106:Vacuum relays
1105:
1103:
1099:
1095:
1091:
1084:
1082:
1080:
1072:
1070:
1068:
1064:
1060:
1056:
1052:
1048:
1044:
1040:
1031:
1024:
1020:
1013:
1011:
1009:
1006:(PLCs), PCs,
1005:
1001:
993:
991:
988:
987:Safety relays
982:Safety relays
981:
979:
976:
974:
968:
966:
962:
958:
954:
950:
946:
937:
930:
928:
926:
922:
914:
912:
910:
906:
900:
898:
892:
888:
886:
881:
873:
871:
864:
862:
858:
855:
851:
846:
844:
840:
831:
824:
822:
819:
818:mercury relay
812:Mercury relay
811:
809:
807:
803:
799:
793:
791:
787:
783:
782:machine tools
775:
773:
771:
766:
764:
763:
758:
754:
749:
747:
743:
740:or the later
739:
735:
730:
728:
723:
721:
717:
712:
710:
705:
704:ratchet relay
700:
698:
693:
688:
686:
680:
678:
674:
670:
666:
662:
653:
646:
644:
640:
636:
632:
625:
623:
621:
617:
613:
609:
601:
599:
597:
593:
588:
580:Coaxial relay
579:
571:
562:
558:
557:
552:
551:
545:
536:
535:
529:
524:
521:
518:
515:
512:
511:
510:
508:
504:
501:
497:
495:
491:
487:
483:
479:
471:
468:
465:
462:
459:
458:
453:
450:
447:
443:
439:
438:
433:
432:
427:
424:
421:
417:
413:
412:
407:
404:
401:
397:
396:
391:
388:
385:
381:
380:
375:
372:
371:
370:
368:
363:
360:
356:
352:
348:
339:
332:
330:
326:
324:
319:
316:
307:
303:
300:
296:
292:
291:semiconductor
289:dangerous to
288:
287:voltage spike
284:
280:
277:
273:
272:flyback diode
269:
247:
245:
240:
236:
231:
229:
225:
220:
216:
212:
208:
199:
192:
191:flyback diode
187:
179:
172:
170:
168:
163:
161:
156:
154:
150:
146:
138:
136:
132:
130:
129:
128:safety relays
124:
123:
118:
114:
113:semiconductor
110:
106:
105:electromagnet
102:
97:
95:
91:
86:
84:
83:contact forms
80:
76:
72:
63:
55:
47:
39:
33:
19:
2308:. Retrieved
2298:
2283:
2271:. Retrieved
2247:. Retrieved
2243:the original
2233:
2221:. Retrieved
2212:
2198:
2181:
2170:. Retrieved
2161:(1): 15β44.
2158:
2154:
2130:. Retrieved
2128:. 2020-02-15
2125:
2116:
2110:: 3β1. 1991.
2103:
2097:
2086:. Retrieved
2081:
2071:
2052:
2046:
2028:
2008:. Retrieved
2006:. 2015-01-13
2003:
1994:
1974:
1967:
1948:
1942:
1926:
1921:
1912:
1903:
1866:
1847:
1841:
1825:
1820:
1809:. Retrieved
1803:
1796:
1784:. Retrieved
1774:
1762:. Retrieved
1758:
1749:
1740:
1731:
1707:September 6,
1705:. Retrieved
1684:
1673:
1665:
1645:
1639:
1628:. Retrieved
1624:the original
1614:
1594:
1588:
1519:
1509:
1503:
1499:
1495:
1484:
1473:
1469:
1454:break rating
1453:
1449:
1447:
1432:
1413:
1393:
1391:loads of 50
1381:acceleration
1305:
1278:
1270:
1263:
1258:interlocking
1238:
1215:
1197:such as the
1192:
1177:
1167:
1143:
1126:
1115:Applications
1109:
1100:
1096:
1092:
1088:
1079:static relay
1076:
1073:Static relay
1036:
997:
985:
977:
969:
942:
918:
905:thermocouple
901:
893:
889:
877:
868:
859:
847:
836:
815:
802:ladder logic
794:
779:
767:
760:
750:
731:
724:
713:
703:
701:
689:
681:
676:
672:
668:
664:
660:
658:
641:
637:
633:
629:
620:silver oxide
605:
587:transceivers
583:
565:
554:
548:
505:
499:
498:
489:
485:
481:
477:
475:
455:
451:
445:
441:
435:
429:
425:
419:
415:
409:
405:
399:
393:
389:
383:
377:
373:
364:
358:
350:
344:
327:
320:
312:
265:
232:
204:
166:
164:
160:Samuel Morse
157:
149:Joseph Henry
142:
133:
126:
120:
117:moving parts
98:
87:
75:electrically
70:
68:
2273:December 6,
2106:(811β814).
1764:16 December
1549:Dry contact
1474:Inside the
1450:make rating
1428:Reed relays
1336:duty cycles
1188:relay logic
1059:optocoupler
1043:solid state
1041:(SSR) is a
1023:Solid-state
949:reed switch
880:overcurrent
798:relay logic
796:functions (
786:form factor
746:1ESS switch
333:Terminology
295:transistors
2345:Categories
2310:October 9,
2249:October 8,
2223:October 6,
2172:2023-03-16
2132:2022-06-13
2088:2017-12-30
2010:2018-04-19
1937:, page 170
1935:008051359X
1834:008051359X
1811:2018-01-07
1786:October 9,
1630:2012-06-21
1580:References
1435:inductance
1416:hysteresis
1397:, or more.
1300:5XB switch
1296:1XB switch
1190:networks.
973:degaussing
945:reed relay
931:Reed relay
854:inductance
211:reluctance
145:telegraphs
111:which use
1759:Swe-Check
1385:aerospace
1163:Fleetwood
1133:telegraph
1051:thyristor
961:corrosion
957:inert gas
953:evacuated
608:contactor
602:Contactor
507:DIN 72552
165:The word
90:telegraph
77:operated
1876:Archived
1717:cite web
1533:See also
1349:assembly
1150:crossbar
1146:Strowger
965:magnetic
850:coalesce
709:headlamp
697:H-bridge
692:remanent
685:avionics
665:bistable
500:EN 50005
494:actuator
420:transfer
355:contacts
347:switches
315:reactive
283:back EMF
279:resistor
233:When an
215:armature
1737:"Relay"
1690:US 1647
1514:snubber
1478:(1ESS)
1401:relays.
1314:number.
1211:Zuse Z3
1207:Zuse Z2
897:dashpot
843:mercury
744:in the
742:remreed
738:ferreed
661:impulse
561:discuss
390:SPST-NC
374:SPST-NO
357:can be
276:snubber
139:History
41:A relay
2366:Relays
2059:
2035:
1982:
1955:
1933:
1854:
1832:
1696:
1653:
1602:
1505:bounce
1439:motors
1209:, and
1193:Early
616:silver
490:double
482:single
470:Form E
464:Form D
457:Form C
437:Form B
431:Form A
411:Form C
395:Form B
379:Form A
359:thrown
244:arcing
219:spring
79:switch
73:is an
18:Relays
2335:Relay
2190:(PDF)
1900:(PDF)
1523:ozone
1510:break
1496:break
1389:shock
1055:TRIAC
947:is a
753:latch
732:Very
677:latch
671:, or
550:split
530:Types
484:) or
400:break
351:poles
167:relay
71:relay
2312:2011
2275:2013
2251:2014
2225:2014
2057:ISBN
2033:ISBN
1980:ISBN
1953:ISBN
1931:ISBN
1873:here
1852:ISBN
1830:ISBN
1788:2011
1766:2020
1723:link
1709:2011
1651:ISBN
1600:ISBN
1500:make
1298:and
1199:ARRA
1148:and
673:stay
669:keep
476:The
452:DPDT
444:and
426:DPST
406:SPDT
384:make
270:, a
228:yoke
2163:doi
1061:(a
955:or
907:or
725:An
563:)
559:. (
434:or
418:or
398:or
382:or
274:or
125:or
2347::
2259:^
2159:43
2157:.
2153:.
2141:^
2124:.
2080:.
2019:^
2002:.
1902:.
1887:^
1757:.
1739:.
1719:}}
1715:{{
1525:,
1502:/
1424:ΞΌs
1420:ms
1225:.
1205:,
1201:,
1159:UK
1077:A
1053:,
1037:A
943:A
927:.
816:A
808:.
748:.
722:.
714:A
667:,
663:,
606:A
446:NC
442:NO
414:,
246:.
131:.
69:A
2314:.
2292:.
2277:.
2253:.
2227:.
2175:.
2165::
2135:.
2091:.
2065:.
2013:.
1988:.
1961:.
1882:.
1860:.
1814:.
1790:.
1768:.
1743:.
1725:)
1711:.
1659:.
1633:.
1608:.
1394:g
570:)
566:(
488:(
486:D
480:(
478:S
34:.
20:)
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
