Module 11 control systems and fundamentals review and supplement questions

Mechanically hel relays and contactors use two coils and a(n)_____mechanism to proving for quiet operation of the circuit.

Latching

If the equipment fails to start with the contactor closed, probable causes would be one contact not closing, burned contacts, or a broken______

Pigtail connection

A(n)_____is used to provide a continuous magnetic flow to the armature when the voltage of the AC waveform is zero

Shading coil

When selecting overload relay for motors, which of the following must be considered?

The motor full-load current

What does the word "normally" refer to in regard to relay contracts

The placement of the contacts when the circuit is de-energized

What is the major difference between a contactor and a motor starter

The stater provides overload protection while a contactor does not.

Which of the following best describes a relay that is used for motor protection?

Thermal overload relay

Special enclosure are required to protect motor controllers from corrosion.

True.

Because filament-type lamps have large inrush currents, standard motor control contactors must be______if used to control this type of load

Derated

On electrical drawings, the_____is the symbol used for denoting low-voltage devices.

Diamond

The approximate inrush current of filament-type lamps is how many times the normal operating current

15 to 17

The highest voltage rating for magnetic relays is

600v

The normal maximum amperage rating of control relay at 600v is

15A

Which of the following best describes a control relay

An electromagnetic device used in control circuits.

Solid-state relays can be controlled by

Both a and b

Unlike contactors, which are generally used to switch power circuits on relatively high-current loads, relays are normally used in low-current____circuits.

Control

What is the normal position of a stop push-button that is used in conjunction with contactors?

Normally closed

If a solid-state relay is used to control a DC circuit, a(n)___is used to connect the load to the line

Power transistors

The function of a shading coil in a contactor is to

Prevent contact chatter and hum

T or F? Most overload relays used on modern motor starters are thermally operated.

True