Ansi Standard Device Designation Numbers

REF5

ANSI Standard
Device Designation Numbers

Copyright 2002 Kilowatt Classroom, LLC.

1)

Master Element is the initiating device, such as a control switch, voltage relay, float switch, etc., which
serves either directly or through such permissive devices as protective and time -delay relays to place an equipment in or out of operation.

2)

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

3)

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

4)

Master Contactor is a device generally controlled by device function 1or the equivalent and the required permissive and protective devices, that serves to make and break the necessary control circuits to place an equipment intooperation under the desired conditions and to take it out of operation under other or abnormal conditions.

5)

Stopping Device is a control device used primarily to shut down an equipment and hold it out of operation.
(This device may be manually or electrically actuated, but excludes the function of electrical lockout [see device function 86] on abnormal conditions.)

6)

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

7)

Anode Circuit Breaker is a device used in the anode circuits of a power rectifier for the primary purpose of
interrupting the rectifier circuit if an arc-back should occur.

8)

Control Power Disconnecting Device is a disconnecting device, such as a knife switch, circuit breaker, orpull-out fuse block, used for the purpose of respectively connecting and disconnecting the source of control
power to and from the control bus or equipment.

9)

Reference Data

Note: control power is considered to include auxiliary power which supplies such apparatus as small motors and
heaters.

Reversing Device is a device that is used for the purpose of reversing a machine field orfor performing any
other reversing functions.

10) Unit Sequence Switch is a switch that is used to change the sequence in which units may be placed in and out
of service in multiple-unit equipments.
11) Reserved for Future Application (USBR assigned - Control Power Transformer).
12) Over-Speed Device is usually a direct-connected speed switch which functions on machine over-speed.
13)Synchronous-Speed Device is a device such as a centrifugal switch, a slip-frequency relay, a voltage relay,
and undercurrent relay , or any type of device that operates at approximately the synchronous speed of a machine.
14) Under-Speed Device is a device that functions when the speed of a machine fall below a pre -determined
value.
15) Speed or Frequency Matching Device is a device thatfunctions to match and hold the speed or frequency of
a machine or of a system equal to, or approximately equal to, that of another machine, source, or system.
16) Reserved for Future Application (USBR assigned - Battery Charging Device).

Note: This excludes devices that perform such shunting operations as may be necessary in the process of starting a
machine by devices 6 or 42, or their equivalent,and also excludes device function 73 that serves for the switching of
resistors.

Sheet 1

17) Shunting or Discharge Switch is a switch that serves to open or to 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).

REF6

ANSI Standard
Device Designation Numbers

Copyright 2002 Kilowatt...