Elementary/Logic Diagrams

Question 1

What is a 33 Device Number?

Answer 1

Position Switch

Question 2

What is a 43 Device Number

Answer 2

Manual Transfer Switch. (Still a type of control switch)

Question 3

What is a 49 Device Number?

Answer 3

AC thermal relay or device. (Thermal overload)

Question 4

What is a 50 Device Number?

Answer 4

Overcurrent Relay or Device. (Instantaneous)

Question 5

What is a 51 Device Number?

Answer 5

Overload Relay (time delayed)

Question 6

What is a 52 Device Number?

Answer 6

AC Circuit Breaker.

Question 7

What is a 62 Device Number?

Answer 7

Time Delay Relay

Question 8

What is a 63 Device Number?

Answer 8

Fluid Level, Pressure, or Flow Relay

Question 9

What is a 72 Device Number?

Answer 9

DC Circuit Breaker

Question 10

What is a 87 Device Number?

Answer 10

Differential Current Relay

Question 11

What is a 88 Device Number?

Answer 11

Motor Starting Contactor

Question 12

What is a 101 Device Number?

Answer 12

Control Switch

Question 13

What is Shelf Condition?

Answer 13

Relay contacts shown in the de-energized condition unless otherwise noted.

Question 14

What is an ‘a’ contact?

Answer 14

Normally OPEN when de-energized.

Question 15

What is a ‘b’ contact?

Answer 15

Normally CLOSED when de-energized.

Question 16

Describe Lights colors and meanings in a control circuit.

Answer 16

1: Green means breaker is OPEN.
2: Red means breaker is CLOSED.
3: White could mean different things (examples: permissive, or component is operating hot).

Question 17

What is anti-pump and what is it for?

Answer 17

Prevents a breaker from re-closing when a breaker trip signal and close signal exist simultaneously.
Also prevents BKR closure when charging motor is not charged or BKR is not in TEST or CONNECT.
Prevents overheat and damage in BKR.

Question 18

Explain the importance of the “Abnormal or Locked-out” alarm on a safety related pump breaker.

Answer 18

VERY IMPORTANT!

Question 19

What is a 5 Device Number?

Answer 19

Stopping Device.

Question 20

What is a 27 Device Number?

Answer 20

AC Under Voltage Relay.

Question 21

For real, Explain the importance of “Abnormal or Locked-out” alarm on safety related pump breaker.

Answer 21

Locked out is used for safety/protection. Both Abnormal and Lock out will give an alarm.
Possible Causes for alarm:
1: Control Switch in Lockout.
2: Breaker not fully racked in.
3: BKR charging spring not fully charged.
4: BKR control fuses blown/pulled.

Question 22

What is an Off- Return Memory device?

Answer 22

Produces an output when an input is present. The output remains until removed by reset signal. A loss of power also acts as a reset signal.

Symbol is a square with a wye in the middle.

Question 23

What is a retentive memory device?

Answer 23

Retains condition of output based on last energized input (regardless of power interruption). When power is lost/restored, output remains until reset.
Symbol is square with vertical line up middle. Left/Right boxes are empty.

Question 24

What is a Retentive Memory with Actuation Block device?

Answer 24

Device wit retentive memory and also includes a function to block the actuation signal by resetting the signal. When reset with the actuation signal present, the device remains reset until the actuation signal goes away and then comes in again.
Symbol is a square with a vertical line up the middle. The boxes have L and R in them (Latch/Reset)