1. Control magnetic relays are used to control small loads.
a. True
b. False
2. Most of the relays used in machine tool control have double-break contacts.
a. True
b. False
3. Relays are used more often to open and close control circuits than to operate power circuits.
a. True
b. False
4. The greatest advantage of relays with mechanical contacts is that they are resistant to shock and vibration.
a. True
b. False
5. Magnetic relays are affected by the electric noise and the voltage spikes induced in the system.
a. True
b. False
Name: Class: Date:
Unit 7 Relays
6. Starters, contactors, and ____ are similar in construction and operation.
a. mechanical thermostats b. symbols
c. breakers d. relays
7. Solid-state relays intended to control the operation of AC loads use an electronic device called a ____ to connect the
load to the line.
a. diac b. triac
c. thyristor d. transducer
8. Solid-state relays generally apply 3 to ____ volts DC to the input to control the operation of the relay.
a. 12 b. 22
c. 32 d. 42
9. One method of eliminating noise and voltage spikes is to use a ____.
a. transient suppressor b. semiconductor
c. temperature-sensitive resistor d. transducer
10. When the moving element of the thermostat control touches the closed contact, the relay closes and ____.
a. is held in this position by a maintaining contact
b. handles the current to a starter coil
c. causes the relay to freeze
d. the current flow bypasses the operating coil
Name: Class: Date:
Unit 7 Relays