Ansi Numbers

Front 1

1) Master Element

Back 1

The initiating device, such as a control switch, etc., that serves, either directly or through such permissive devices as protective and time-delay relays, to place equipment in or out of operation.

Front 2

2) Time-delay Starting or Closing Relay

Back 2

A device that functions to give a desired amount of time delay before or after any point of operation in a switching sequence or protective relay system, except as specifically provided by device functions 48, 62, and 79.

Front 3

3) Checking or Interlocking Relay

Back 3

A relay that operates in response to the position of a number of other devices (or to a number of predetermined conditions) in equipment to allow an operating sequence to proceed, stop, or provide a check of the position of these devices or conditions for any purpose.

Front 4

4) Master Contactor

Back 4

A device, generally controlled by device function 1 or the equivalent and the required permissive and protective devices, that serves to make and break the necessary control circuits to place equipment into operation under the desired conditions and to take it out of operation under abnormal conditions.

Front 5

5) Stopping Device

Back 5

A control device used primarily to shut down equipment and hold it out of operation.

Front 6

15) Speed or Frequency Matching Device

Back 6

A device that functions to match and hold the speed or frequency of a machine or a system equal to, or approximately equal to, that of another machine, source, or system.

Front 7

16) Reserved For Future Application

Back 7

N/A

Front 8

17) Shunting or Discharge Switch

Back 8

A switch 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.

Front 9

18) Accelerating or Decelerating Device

Back 9

A device that is used to close or cause the closing of circuits that are used to increase or decrease the speed of a machine.

Front 10

19) Starting-to-running Transition Contactor

Back 10

A device that operates to initiate or cause the automatic transfer of a machine from the starting to the running power connection.

Front 11

20) Electrically Operated Valve

Back 11

An electrically operated, controlled, or monitored valve used in a fluid, air, gas, or vacuum line.

Front 12

21) Distance Relay

Back 12

A relay that functions when the circuit admittance, impedance, or reactance increases or decreases beyond a predetermined value.

Front 13

22) Equalizer Circuit Breaker

Back 13

A breaker that serves to control or make and break the equalizer or the current-balancing connections for a machine field, or for regulating equipment, in a multiple-unit installation.

Front 14

23) Temperature Control Device

Back 14

A device that functions to raise or lower the temperature of a machine or other apparatus, or of any medium, when its temperature falls below or rises above a predetermined value.

Front 15

24) Volts Per Hertz Relay

Back 15

A relay that functions when the ratio of voltage to frequency exceeds a preset value. The relay may have an instantaneous or a time characteristic.

Front 16

6) Starting Circuit Breaker

Back 16

A device whose principal function is to connect a machine to its source of starting voltage.

Front 17

25) Sychronizing or Synchronism-check Device

Back 17

A device that operates when two ac circuits are within the desired limits of frequency, phase angle, and voltage to permit or cause the paralleling of these two circuits.

Front 18

26) Apparatus Thermal Device

Back 18

A device that functions when the temperature of the protected apparatus (other than the load carrying windings of machines and transformers as covered by device function number 49) or of a liquid or other medium exceeds a predetermined value; or when the temperature of the protected apparatus or of any medium decreases below a predetermined value.

Front 19

27) Undervoltage relay

Back 19

A relay that operates when its input voltage is less than a predetermined value.

Front 20

28) Flame Detector

Back 20

A device that monitors the presence of the pilot or main flame in such apparatus as a gas turbine or a steam boiler.

Front 21

29) Isolating Contactor

Back 21

A device that is used expressly for disconnecting one circuit from another for the purposes of emergency operation, maintenance, or test.

Front 22

30) Annunciator Relay

Back 22

A nonautomatically reset device that gives a number of separate visual indications upon the functioning of protective devices and that may also be arranged to perform a lockout function.

Front 23

7) Rate-of-rise Relay

Back 23

A relay that functions on an excessive rate-of-rise of current.

Front 24

8) Control Power Disconnecting Device

Back 24

A disconnecting device, such as a knife switch, circuit breaker, or pull-out fuse block, used for the purpose of respec- tively connecting and disconnecting the source of control power to and from the control bus or equipment.

Front 25

9) Reversing Device

Back 25

A device that is used for the purpose of reversing a machine field or for performing any other reversing functions.

Front 26

10) Unit Sequence Switch

Back 26

A switch that is used to change the sequence in which units may be placed in and out of service in multiple-unit equipment.

Front 27

11) Multifunction Device

Back 27

A device that performs three or more comparatively important functions that could only be designated by combining several of these device function numbers.

Front 28

12) Overspeed Device

Back 28

Usually, a direct-connected speed switch that functions on machine overspeed.

Front 29

13) Synchronous-speed Device

Back 29

A device such as a centrifugal-speed switch, a slip-frequency relay, a voltage relay, an under-current relay, or any other type of device that operates at approximately the synchronous speed of a machine.

Front 30

14) Underspeed Device

Back 30

A device that functions when the speed of a machine falls below a predetermined value.

Front 31

5) Stopping Device

Back 31

A control device used primarily to shut down equipment and hold it out of operation.

Front 32

15) Speed or Frequency Matching Device

Back 32

A device that functions to match and hold the speed or frequency of a machine or a system equal to, or approximately equal to, that of another machine, source, or system.

Front 33

16) Reserved For Future Application

Back 33

N/A

Front 34

17) Shunting or Discharge Switch

Back 34

A switch 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.

Front 35

18) Accelerating or Decelerating Device

Back 35

A device that is used to close or cause the closing of circuits that are used to increase or decrease the speed of a machine.

Front 36

19) Starting-to-running Transition Contactor

Back 36

A device that operates to initiate or cause the automatic transfer of a machine from the starting to the running power connection.

Front 37

20) Electrically Operated Valve

Back 37

An electrically operated, controlled, or monitored valve used in a fluid, air, gas, or vacuum line.

Front 38

21) Distance Relay

Back 38

A relay that functions when the circuit admittance, impedance, or reactance increases or decreases beyond a predetermined value.

Front 39

22) Equalizer Circuit Breaker

Back 39

A breaker that serves to control or make and break the equalizer or the current-balancing connections for a machine field, or for regulating equipment, in a multiple-unit installation.

Front 40

23) Temperature Control Device

Back 40

A device that functions to raise or lower the temperature of a machine or other apparatus, or of any medium, when its temperature falls below or rises above a predetermined value.

Front 41

24) Volts Per Hertz Relay

Back 41

A relay that functions when the ratio of voltage to frequency exceeds a preset value. The relay may have an instantaneous or a time characteristic.

Front 42

6) Starting Circuit Breaker

Back 42

A device whose principal function is to connect a machine to its source of starting voltage.

Front 43

25) Sychronizing or Synchronism-check Device

Back 43

A device that operates when two ac circuits are within the desired limits of frequency, phase angle, and voltage to permit or cause the paralleling of these two circuits.

Front 44

26) Apparatus Thermal Device

Back 44

A device that functions when the temperature of the protected apparatus (other than the load carrying windings of machines and transformers as covered by device function number 49) or of a liquid or other medium exceeds a predetermined value; or when the temperature of the protected apparatus or of any medium decreases below a predetermined value.

Front 45

27) Undervoltage relay

Back 45

A relay that operates when its input voltage is less than a predetermined value.

Front 46

28) Flame Detector

Back 46

A device that monitors the presence of the pilot or main flame in such apparatus as a gas turbine or a steam boiler.

Front 47

29) Isolating Contactor

Back 47

A device that is used expressly for disconnecting one circuit from another for the purposes of emergency operation, maintenance, or test.

Front 48

30) Annunciator Relay

Back 48

A nonautomatically reset device that gives a number of separate visual indications upon the functioning of protective devices and that may also be arranged to perform a lockout function.

Front 49

7) Rate-of-rise Relay

Back 49

A relay that functions on an excessive rate-of-rise of current.

Front 50

8) Control Power Disconnecting Device

Back 50

A disconnecting device, such as a knife switch, circuit breaker, or pull-out fuse block, used for the purpose of respec- tively connecting and disconnecting the source of control power to and from the control bus or equipment.

Front 51

9) Reversing Device

Back 51

A device that is used for the purpose of reversing a machine field or for performing any other reversing functions.

Front 52

10) Unit Sequence Switch

Back 52

A switch that is used to change the sequence in which units may be placed in and out of service in multiple-unit equipment.

Front 53

11) Multifunction Device

Back 53

A device that performs three or more comparatively important functions that could only be designated by combining several of these device function numbers.

Front 54

12) Overspeed Device

Back 54

Usually, a direct-connected speed switch that functions on machine overspeed.

Front 55

13) Synchronous-speed Device

Back 55

A device such as a centrifugal-speed switch, a slip-frequency relay, a voltage relay, an under-current relay, or any other type of device that operates at approximately the synchronous speed of a machine.

Front 56

14) Underspeed Device

Back 56

A device that functions when the speed of a machine falls below a predetermined value.