21-30 Definitions

Question 1

Impedance Relay

Answer 1

One which functions when the circuit impedance increases or decreases to a predetermined value

Question 2

Equalizer Circuit Breaker or Contactor

Answer 2

Serves to make and break the equalizer or current-balancing connections for machine field, or voltage regulator

Question 3

Temperature Regulating Device

Answer 3

One which functions to hold the temperature of a machine or other apparatus between certain limits

Question 4

Bus Tie Circuit Breaker, Contactor or Switch

Answer 4

Serves to connect buses or bus sections together

Question 5

Synchronizing or Parallel Device

Answer 5

One which operates when two A-C Circuits are within the desired limits of voltage, frequency and/or phase angle, to cause the paralleling of these two circuits

Question 6

Apparatus Thermal Device

Answer 6

One which functions at desired high and/or low operating-temperature values or limits of the apparatus to which it is applied

Question 7

A-C Undervoltage Relay

Answer 7

One which functions on a given value of single-phase A-C undervoltage

Question 8

Resistor Thermal Device

Answer 8

One which functions upon excessive load indicating, limiting, or shifting resistor temperature

Question 9

Isolating Circuit Breaker, Contactor or Switch

Answer 9

One used for the express purpose of disconnecting one circuit from another

Question 10

Annunciator Relay

Answer 10

A non-automatic reset device which gives a number of separate visual indications upon the functioning of protective devices