Control Transformers

Question 1

The sealed current called ___ implies that relays and solenoids are pulled in.

A) inrush current
B) inrush load power factor
C) steady-state current

Answer 1

C) steady-state current

Question 2

A(n) ___ is an overcurrent condition that leaves the normal current path and greatly exceeds the normal full load current of the circuit.

A) overload
B) short circuit

Answer 2

B) short circuit

Question 3

Some industrial applications require fuse protection on one ___ line and in both ___ lines.

A) primary / secondary
B) secondary / primary

Answer 3

B) secondary / primary

Question 4

When connecting a control transformer with dual windings in both primary and secondary coils, to step down from 480 V AC to 120 V AC the primary windings are connected ___ and the secondary windings are connected in ___.

A) parallel / parallel
B) parallel / series
C) series / parallel
D) series / series

Answer 4

C) series / parallel

Question 5

The ___ system is the most common for industrial control applications.

A) floating
B) grounded

Answer 5

B) grounded

Question 6

Control transformer suppliers reccomend fuse sizes based on the ___.

A) IEEE
B) NEC
C) NEMA
D) NESC

Answer 6

B) NEC

Question 7

AC circuits of ___ or more must be grounded in accordance with the NEC Section 250.

A) 24 V
B) 50 V
C) 100 V
D) 150 V

Answer 7

B) 50 V

Question 8

The wiring terminals of a control transformer are connected with a metal clip to minimize the chatter.

A) True
B) False

Answer 8

B) False

Question 9

When the terminals of a control transformer have to be linked by wire, the manufacturer-recommended wire types and sizes should be used.

A) True
B) False

Answer 9

A) True

Question 10

The NEMA standard specifies that AC magnetic motor starting devices must function at voltages as low as ___ of the rates coil voltage.

A) 50%
B) 75%
C) 85%
D) 90%

Answer 10

C) 85%

Question 11

Generally, control transformers step down the main line voltage to a control voltage of ___ or ___.

A) 120 VAC / 24 VAC
B) 120 VAC / 48VAC
C) 208 VAC / 120 VAC
D) 240 VAC / 120 VAC

Answer 11

A) 120 VAC / 24 VAC

Question 12

The use of fuses on the primary and secondary side of a control transformer is specified by the ___.

A) IEEE
B) NEC
C) NEMA
D) NESC

Answer 12

B) NEC

Question 13

A(n) ___ is any current flow in the normal current path that is higher than the circuit’s normal full load current.

A) overload
B) short circuit

Answer 13

A) overload