322

Where the maximum line current of a 3Ø load is 60 amps, a 3-pole NEMA contactor should have a rating that is at least ___ amps.

60

EMR is an abbreviation for ___.

Electro-Mechanical Relay

all of these

Refer to Figure 324.45. The current time is 9 pm. When the HOA switch is in the AUTO position, ___ is energized.I. the TC motor II. the white light III. the green light IV. the transformer V. relay R1 The ON tripper is set at 7 pm and the OFF tripper is set at 6 am. I & IV only I,II, III & IV only I, II & IV only I, IV & V only

none of these

Refer to Figure 324.46. The current time is 7 am. When the HOA switch is in the AUTO position, ___ is energized.I. relay R2 II. the white light III. the green light The ON tripper is set at 7 pm and the OFF tripper is set at 6 am.

neither white or green

Refer to Figure 324.47. The current time is 1 pm. When the HOA switch is in the AUTO position, the ___ light is energized. The weather conditions here in Kansas are clear skies with a northwest wind at 7-10 mph.

white & green

Refer to Figure 324.47. The current time is 11 pm. When the HOA switch is in the AUTO position, the ___ light is energized. The weather conditions here in Kansas are clear skies with a northwest wind at 7-10 mph.

4

Refer to Figure 324.52. Point J on the ladder diagram should be connected at terminal ___ on the equipment.

7

Refer to Figure 324.53. Point G on the ladder diagram should be connected at terminal ___ on the equipment.

2 & 10

Refer to the relay wiring diagram shown in Figure 321.24. The coil is connected between terminals ___.

3PDT

Refer to the relay wiring diagram shown in Figure 321.24. This is a(n) ___ relay.

SSR is an abbreviation for ___.

Solid-State Relay

Z, V & W

The circuit breaker should be connected to points ___ in Figure 323.5. A 120-V photocell is to be used to operate a lighting contactor. The contactor controls three, separate, 277-V circuits that are supplied from a 3-Pole circuit breaker.

120

The contactor shown in Figure 323.5 should have a coil that is rated for ___ volts. A 120-V photocell is to be used to operate a lighting contactor. The contactor controls three, separate, 277-V circuits that are supplied from a 3-Pole circuit breaker.

Power to the loads in a 230-volt circuit can be controlled by a relay that opens and closes contacts in a 24-volt circuit.

True

Where a relay contains one set of NO and one set of NC contacts, these are interlocked so that they are always in opposite states.

True

The four basic switching types for SSRs include ___. zero switching instant-on peak switching analog switching

all of these

Solenoids, relays, starters, and contactors utilize ___ to cause an armature to move.

an electromagnet

The coil of an EMR performs the same function as ___ of an SSR.

an input circuit

In a control circuit which of these drawings shows the components connected to operate correctly?

b

Select (as required) the NEMA symbol for a normally closed set of contacts (contained in a relay or a contact block).

b

General-purpose (ice-cube-type) relays ___ have replaceable contacts.

do not

A contactor, that closes when power is applied to the coil and releases when power is removed, is referred to as ___ held.

electrically

A 230-volt coil has an impedance that is ___ a 115-volt coil. Both have 600 VA inrush ratings.

higher than

As the current through a relay coil increases, the magnetic field around the coil ___.

increases

The failure rate of SSRs ___ as the ambient temperature increases.

increases

It ___ permitted to use a double-pole manual contactor to control a thermally-protected, 1-phase 240-volt motor.

is

The coil rating on the equipment shown in Figure 321.21 ___.

is 120 volts

For general-purpose relays, the contact current rating for switching DC is ___ the contact rating for switching AC.

lower than

The coils contained within solenoids, relays, starters, and contactors ___ when they fail.

must be replaced

In a numerical cross-reference system, ___ contacts are underlined.

normally closed

To help dissipate the heat generated within an SSR, the relays are mounted ___.

on heat sinks

Generally, SSRs have ___ output contact(s).

only one

To help prevent overvoltage problems, a varistor is connected between the ___ terminals of an SSR.

output

Refer to Figure 321.11. Equipment I is a ___.

relay

0 to 0.2

Refer to Figure 321.21. An ohmmeter reading between Points H & N would indicate ___ Ω. The equipment shown is not energized.The equipment shown is not connected to anything else.

10 to 400

Refer to Figure 321.21. An ohmmeter reading between Points L & R would indicate ___ Ω. The equipment shown is not energized.The equipment shown is not connected to anything else.

12

Refer to Figure 321.22. The contacts of this equipment have a rating of ___ amps at 120 volts.

2 only

Refer to Figure 324.41. Time clock terminal 4 should be connected to terminal ___ on the relay. Through a relay, a 240-volt load is to be controlled by a time clock. The load circuit is LD-4-6. The load is to be ON when the TC switch is ON. The control circuit is LA-1. The clock motor and the relay coil require 120 volts.

d

Refer to Figure 324.41. Which of the diagrams, shown below, would correctly operate the load as required? Through a relay, a 240-volt load is to be controlled by a time clock. The load circuit is LD-4-6. The load is to be ON when the TC switch is ON. The control circuit is LA-1. The clock motor and the relay coil require 120 volts.

2 only

Refer to Figure 324.42. The control circuit neutral could be connected to terminal(s) ___ on the relay. Through a relay with a 120-volt coil, a 240-volt fan is to be controlled by a time clock that has a 120-volt clock motor. The 120-volt control circuit is LA-1. The fan runs only when the TC switch is closed.

1 & 8

Refer to Figure 324.42. The two 240-volt wires connected to terminals ___ on the relay. Through a relay with a 120-volt coil, a 240-volt fan is to be controlled by a time clock that has a 120-volt clock motor. The 120-volt control circuit is LA-1. The fan runs only when the TC switch is closed.

I only

Refer to Figure 324.43. Which of the diagrams, shown below, would correctly operate the load as required? Through a relay, a fan is to be controlled by a time clock that has a 120-volt clock motor. Both the relay coil and the fan operate at 24 volts. The 120-volt control circuit is LA-1. The fan runs only when the TC switch is closed.

I & IV only

Refer to Figure 324.45. The current time is 8 am. When the HOA switch is in the AUTO position, ___ is energized. I. the TC motor II. the white light III. the green light IV. the transformer V. relay R1 The ON tripper is set at 7 pm and the OFF tripper is set at 6 am.