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Device number 1
A device, such as a control switch, etc., that serves, either directly or through such permissive devices asprotective and time-delay relays, to place equipment in or out of operation.
Device number 2
time-delay starting or closing relay
A device that functions to give a desired amount of time delay before or after any point of operation in aswitching sequence or protective relay system, except as specifically provided by device functions 48, 62,79, and 82.
Device number 3
checking or interlocking relay
A device that operates in response to the position of one or more other devices or predetermined conditionsin a piece of equipment or circuit, to allow an operating sequence to proceed, or to stop, or to provide acheck of the position of these devices or conditions for any purpose.
Device number 4
A device, generally controlled by device function l or the equivalent and the required permissive andprotective devices, that serves to make and break the necessary control circuits to place equipment intooperation under the desired conditions and to take it out of operation under abnormal conditions.
Device number 5
A control device used primarily to shut down equipment and hold it out of operation. [This device may bemanually or electrically actuated, but it excludes the function of electrical lockout (see device function 86)on abnormal conditions.
Device number 6
starting circuit breaker
A device whose principal function is to connect a machine to its source of starting voltage
Device number 7
A device that operates when the rate-of-change of the measured quantity exceeds a threshold value, exceptas defined by device 63.
Device number 8
control power disconnecting device
A device, such as a knife switch, circuit breaker, or pull-out fuse block, used for the purpose of connectingand disconnecting the source of control power to and from the control bus or equipment.
Device number 9
A device that is used for the purpose of reversing the field of a machine or for performing any otherreversing function
Device number 10
unit sequence switch
A device that is used to change the sequence in which units may be placed in and out of service in multipleunitequipmen
Device number 11
A device that performs three or more comparatively important functions that could only be designated bycombining several device function numbers. All of the functions performed by device 11 shall be defined inthe drawing legend, device function definition list, or relay-setting record. See Annex A for furtherdiscussion and examples.
Device number 12
A device, usually direct-connected, that operates on machine overspeed.
Device number 13
A device such as a centrifugal-speed switch, a slip-frequency relay, a voltage relay, an undercurrent relay,or any other type of device that operates at approximately the synchronous speed of a machine
Device number 14
A device that functions when the speed of a machine falls below a predetermined value.
Device number 15
speed or frequency matching device
A device that functions to match and hold the speed or frequency of a machine or a system equal to, orapproximately equal to, that of another machine, source, or system.
Device number 16
reserved for future application
Device number 17
shunting or discharge switch
A device that serves to open or close a shunting circuit around any piece of apparatus (except a resistor),such as a machine field, a machine armature, a capacitor, or a reactor
Device number 18
accelerating or decelerating deviceA device that is used to close or cause the closing of circuits that are used to increase or decrease the speedof a machine
Device number 19
starting-to-running transition contactor
A device that operates to initiate or cause the automatic transfer of a machine from the starting to therunning power connection.
Device number 20
electrically operated valve
An electrically-operated or -controlled device used in a fluid, air, gas, or vacuum line.
Device number 21
A device that functions when the circuit admittance, impedance, or reactance increases or decreases beyonda predetermined value.
Device number 22
equalizer circuit breaker
A device that serves to control or make and break the equalizer or the current balancing connections for amachine field, or for regulating equipment, in a multi-unit installation.
Device number 23
temperature control device
A device that functions to control the temperature of a machine or other apparatus, or of any medium, whenits temperature falls below or rises above a predetermined value.
Device number 24
volts per Hertz relay
A device that operates when the ratio of voltage to frequency is above a preset value or is below a differentpreset value. The relay may have any combination of instantaneous or time-delayed characteristics.
Device number 25
synchronizing or synchronism-check relay
A synchronizing device that produces an output that causes closure of a circuit breaker between twocircuits whose voltages are within prescribed limits of magnitude, phase angle, and frequency. It may ormay not include voltage or speed control. A synchronism-check relay permits the paralleling of two circuitsthat are within prescribed (usually wider) limits of voltage magnitude, phase angle, and frequency.
Device number 26
apparatus thermal device
A device that functions when the temperature of the protected apparatus (other than the load-carryingwindings of machines and transformers as covered by device function number 49), or that of a liquid orother medium, exceeds a predetermined value; or when the temperature of the protected apparatus or that ofa liquid or other medium,exceeds a predetermined value or decreases below a predetermined value.
Device number 27
A device that operates when its input voltage is less than a predetermined value
Device number 28
A device that monitors the presence of the pilot or main flame in such apparatus as a gas turbine or a steamboiler
Device number 29
isolating contactor or switch
A device that is used expressly for disconnecting one circuit from another for the purposes of emergencyoperation, maintenance, or testing.
Device number 30
A nonautomatically reset device that gives a number of separate visual indications upon the functioning ofprotective devices and that may also be arranged to perform a lockout function.
Device number 31
separate excitation device
A device that connects a circuit, such as the shunt field of a synchronous converter, to a source of separateexcitation during the starting sequence.
Device number 32
directional power relay
A device that operates on a predetermined value of power flow in a given direction, such as reverse powerflow resulting from the motoring of a generator upon loss of its prime mover
Device number 33
A device that makes or breaks contact when the main device or piece of apparatus that has no devicefunction number reaches a given position.
Device number 34
master sequence device
A device such as a motor-operated multi-contact switch (or the equivalent), or a programmable device, thatestablishes or determines the operating sequence of the major devices in equipment during starting andstopping, or during sequential switching operations.
Device number 35
brush-operating or slip-ring short-circuiting device
A device for raising, lowering, or shifting the brushes of a machine; short-circuiting its slip rings; orengaging or disengaging the contacts of a mechanical rectifier.
Device number 36
polarity or polarizing voltage device
A device that operates, or permits the operation of, another device on a predetermined polarity only, or thatverifies the presence of a polarizing voltage in equipment.
Device number 37
undercurrent or underpower relay
A device that functions when the current or power flow decreases below a predetermined value
Device number 38
bearing protective device
A device that activates upon excessive bearing temperature or on other abnormal mechanical conditionsassociated with bearings, such as undue wear, which may eventually result in excessive bearing temperature or failure.
Device number 39
mechanical condition monitor
A device that activates upon the occurrence of an abnormal mechanical condition (except conditions associated with bearings as covered under device function 38), such as excessive vibration, eccentricity, expansion, shock, tilting, or seal failure.
Device number 40
A device that activates upon a given or abnormally high or low value or failure of machine field current, oron an excessive value of the reactive component of armature current in an ac machine indicatingabnormally high or low field excitation.
Device number 41
field circuit breaker
A device that functions to apply or remove the field excitation of a machine.
Device number 42
running circuit breaker
A device whose function is to connect a machine to its source of running or operating voltage. This function may also be used for a device, such as a contactor, that is used in series with a circuit breaker or other fault-protecting means, primarily for frequent opening and closing of the circuit.
Device number 43
manual transfer or selector device
A manually operated device that transfers control or potential circuits in order to modify the plan ofoperation of the associated equipment or of some of the associated devices
Device number 44
unit sequence starting relay
A device that functions to start the next available unit in multiple-unit equipment upon the failure or nonavailabilityof the normally preceding unit.
Device number 45
atmospheric condition monitor
A device that functions upon the occurrence of an abnormal atmospheric condition, such as damagingfumes, explosive mixtures, smoke, or fire.
Device number 46
reverse-phase or phase-balance current relay
A device in a polyphase circuit that operates when the polyphase currents are of reverse-phase sequence, orwhen the polyphase currents are unbalanced, or when the negative phase-sequence current exceeds a presetvalue.
Device number 47
phase-sequence or phase-balance voltage relay
A device in a polyphase circuit that functions upon a predetermined value of polyphase voltage in thedesired phase sequence when the polyphase voltages are unbalanced, or when the negative phase-sequence voltage exceeds a preset value.
Device number 48
incomplete sequence relay
A device that returns the equipment to the normal or off position and locks it out if the normal starting,operating, or stopping sequence is not properly completed within a predetermined time.
Device number 49
machine or transformer thermal relay
A device that functions when the temperature of a machine armature winding or other load-carryingwinding or element of a machine or power transformer exceeds a predetermined value.
Device number 50
instantaneous overcurrent relay
A device that operates with no intentional time delay when the current exceeds a preset value. The suffixTD should be used (e.g., 50TD) to describe a definite time overcurrent function. Use 50BF for a current monitored breaker failure function.
Device number 51
ac time overcurrent relay
A device that functions when the ac input current exceeds a predetermined value, and in which the inputcurrent and operating time are inversely related through a substantial portion of the performance range.
Device number 52
ac circuit breaker
A device that is used to close and interrupt an ac power circuit under normal conditions or to interrupt thiscircuit under fault or emergency conditions.
Device number 53
exciter or dc generator relay
A device that forces the dc machine field excitation to build up during starting or that functions when themachine voltage has built up to a given value.
Device number 54
turning gear engaging device
A device either electrically operated, controlled, or monitored that functions to cause the turning gear to engage (or disengage) the machine shaft.
Device number 55
power factor relay
A device that operates when the power factor in an ac circuit rises above or falls below a predeterminedvalue.
Device number 56
field application relay
A device that automatically controls the application of the field excitation to a synchronous ac motor atsome predetermined point in the slip cycle.
Device number 57
short-circuiting or grounding device
A device that functions to short-circuit or ground a circuit in response to automatic or manual means.
Device number 58
rectification failure relayA device that functions if a power rectifier (diode) fails to conduct or block properly
Device number 59
A device that operates when its input voltage exceeds a predetermined value
Device number 60
voltage or current balance relay
A device that operates on a given difference in voltage, or current input or output, of two circuits.
Device number 61
density switch or sensor
A device that operates at a given density value or at a given rate of change of density.a
Device number 62
time-delay stopping or opening relay
A device that imposes a time delay in conjunction with the device that initiates the shutdown, stopping, oropening operation in an automatic sequence.
Device number 63
A device that operates at a given pressure value or at a given rate of change of pressure.
Device number 64
ground detector relay
A device that operates upon the insulation failure of a machine or other apparatus to ground
Device number 65
A device consisting of an assembly of fluid, electrical, or mechanical control equipment used for regulatingthe flow of water, steam, or other media to the prime mover for such purposes as starting, holding speed orload, or stopping.
Device number 66
notching or jogging device
A device that functions to allow only a specified number of operations of a given device or piece ofequipment, or a specified number of successive operations within a given time of each other. It is also adevice that functions to energize a circuit periodically or for fractions of specified time intervals, or that isused to permit intermittent acceleration or jogging of a machine at low speeds for mechanical positioning.
Device number 67
ac directional overcurrent relay
A device that functions at a desired value of ac overcurrent flowing in a predetermined direction.
Device number 68
blocking or “out-of-step” relay
A device that initiates a pilot signal for blocking of tripping on external faults in a transmission line or inother apparatus under predetermined conditions, or cooperates with other devices to block tripping orreclosing on an out-of-step condition or on power swings.
Device number 69
permissive control device
A device with two positions that, in one position permits the closing of a circuit breaker, or the placing of a piece of equipment into operation, and in the other position, prevents the circuit breaker or the equipment from being operated.
Device number 70
A device used to vary the resistance in an electric circuit when the device is electrically operated or hasother electrical accessories, such as auxiliary, position, or limit switches.
Device number 71
A device that operates at a given level value, or on a given rate of change of level
Device number 72
dc circuit breaker
A device that is used to close and interrupt a dc power circuit under normal conditions or to interrupt thiscircuit under fault or emergency conditions.
Device number 73
A device that is used to shunt or insert a step of load limiting, shifting, or indicating resistance in a power circuit; to switch a space heater in circuit; or to switch a light or regenerative load resistor of a power rectifier or other machine in and out of circuit.
Device number 74
A device other than an annunciator, as covered under device function 30, that is used to operate, or thatoperates in connection with, a visual or audible alarm.
Device number 75
position changing mechanism
A device that is used for moving a main device from one position to another in equipment; for example,shifting a removable circuit breaker unit to and from the connected, disconnected, and test positions.
Device number 76
dc overcurrent relay
A device that functions when the current in a dc circuit exceeds a given value.
Device number 77
A transmitting device used to generate and transmit to a remote location an electrical signal representing ameasured quantity; or a receiver used to receive the electrical signal from a remote transmitter and convertthe signal to represent the original measured quantity.
Device number 78
phase-angle measuring relay
A device that functions at a predetermined phase angle between two voltages, between two currents, orbetween a voltage and a current.
Device number 79
A device that controls the automatic reclosing and locking out of an ac circuit breaker.
Device number 80
A device that operates at a given flow value, or at a given rate of change of flow.
Device number 81
A device that responds to the frequency of an electrical quantity, operating when the frequency or rate ofchange of frequency exceeds or is less than a predetermined value.
Device number 82
dc load-measuring reclosing relay
A device that controls the automatic closing and reclosing of a dc circuit interrupter, generally in responseto load circuit conditions.
Device number 83
automatic selective control or transfer relay
A device that operates to select automatically between certain sources or conditions in equipment or thatperforms a transfer operation automatically.
Device number 84
A device consisting of the complete electrical mechanism or servomechanism, including the operating motor, solenoids, position switches, etc., for a tap changer, induction regulator, or any similar piece of apparatus that otherwise has no device function number.
Device number 85
carrier or pilot-wire relay
A device that is operated, restrained by signal transmitted or received via any communications media used for relaying
Device number 86
A device that trips and maintains the associated equipment or devices as inoperative until it is reset by anoperator, either locally or remotely.
Device number 87
differential protective relay
A device that operates on a percentage, phase angle, or other quantitative difference of two or morecurrents or other electrical quantities.
Device number 88
auxiliary motor or motor generator
A device used for operating auxiliary equipment, such as pumps, blowers, exciters, rotating magneticamplifiers, etc.
Device number 89
A device used as a disconnecting, load-interrupter, circuit switcher, or isolating switch in an ac or dc powercircuit. (This device function number is normally not necessary unless the switch is electrically operated orhas electrical accessories, such as an auxiliary switch, a magnetic lock, etc.)
Device number 90
A device that functions to regulate a quantity or quantities, such as voltage, current, power, speed, frequency, temperature, and load, at a certain value or between certain (generally close) limits formachines, tie lines, or other apparatus.
Device number 91
voltage directional relay
A device that operates when the voltage across an open circuit breaker or contactor exceeds a given valuein a given direction.
Device number 92
voltage and power directional relay
A device that permits or causes the connection of two circuits when the voltage difference between themexceeds a given value in a predetermined direction and causes these two circuits to be disconnected fromeach other when the power flowing between them exceeds a given value in the opposite direction.
Device number 93
A device that functions to increase or decrease, in one step, the value of field excitation on a machine.
Device number 94
tripping or trip-free relay
A self-resetting device that functions to trip a circuit breaker, contactor, or piece of equipment; to permitimmediate tripping by other devices; or to prevent immediate reclosing of a circuit interrupter if it shouldopen automatically, even though its closing circuit is activated or energized
Device numbers 95–99
used only for specific applications