12 27

Question 1

A fuse may serve the same purpose in isolating a fault as a

Answer 1

Circuit breaker

Question 2

From the below list of fuse characteristics, select the one that is not true:

Answer 2

All fuses are completely non-repetetive in design

Question 3

The primary reason for not replacing a blown fuse with a piece of copper wire is because:

Answer 3

The desired circuit protection against overload may be lost

Question 4

The term zones of protection applies most nearly to the isolation of faulted equipment

Answer 4

Throughout the entire power system

Question 5

A device which recieves some type of signal from an electric circuit and responds to the signal by sending out or relaying a modified signal to the same or another electric circuit

Answer 5

Relay

Question 6

Protective relays, in general, must be able to:

Answer 6

All of the above

• Isolate faults from rest of system
• Trip only breakers connected to faulty equipment
• Differentiate between permissible op conditions and abormal or fault conditions

Question 7

Protective relays may be classified in all of the below ways except:

Answer 7

According to the manner in which they are connected in the circuit

Question 8

An induction-disc time overcurrent relay:

Answer 8

Is adjusted separately for the degree of overcurrent at which it operates and also for the amount if time delay

Question 9

Differential current relays are designed and installed to protect against

Answer 9

Internal faults

Question 10

When CTs are used w/ protective relays, the direction of current flows in the transformer windings (polarity marks):

Answer 10

Must be carefully observed for relay types which depend on the interaction of 2 currents for their action

Question 11

All of the following statements concerning the schematic shown in Fig 28 are true except for:

Answer 11

???

Question 12

A device which normally responds to changes in circuit admittance, impedance or reactance increases or decreases beyond predetermined limits is called a

Answer 12

Distance relay

Question 13

A relay used to protect polyphase rotating equipment from single or unbalanced phase operation is a ___________ relay

Answer 13

Phase-balance

Question 14

The protective device for a motor branch circuit should:

Answer 14

Not be of the instantaneous type

Question 15

The induction disc time overcurrent relay has which characteristics?

Answer 15

Both a and b

Definite
Inverse-time