Unit 19 Review

A common practice in condensing units is to use a contactor with only one set of contacts opening only one side of the power to the unit. This is to ____.

• reduce the cost of the contactor
• make it easier to wire the unit
• teach the service technician not to put hands in the unit with the power on
• provide off-cycle heat to the compressor

An inherent motor protector is a ____ .

• circuit breaker
• motor starter overload
• thermally activated device in the motor winding
• line fuse

Beside maintaining pressure on the contacts for current carrying capacity, the pressure springs have a second important function. This is to ____.

• keep the contacts in line
• help obtain equal contacts against the stationary contacts
• slow down the pull of the armature into place to reduce the noise
• increase the power required to close the contacts

Technician "A" says that if you take a voltage reading from terminal L1 to terminal T1 on a contactor whose coil is energized, you should read zero volts. Technician "B" says that contactors can only have normally open contacts. Which of the following statements is correct?

• Technician A is correct. Technician B is correct.
• Technician A is correct. Technician B is incorrect.
• Technician A is incorrect. Technician B is correct.
• Technician A is incorrect. Technician B is incorrect.

The __ in a contactor keeps equal tension on all all contact surfaces

• stationary contacts
• holding coil
• springs
• movable contacts

The motor starter has ____.

• a belt and pulley
• a start compacitor
• one or more overload protectors,magnetic coil, and electrical contacts
• been replaced by a potential relay

The service factor of an electric motor is determined by ____.

• National Electrical Code
• National Electrical Manufacturers Association code
• motor's reserve capacity
• none of these

When a contactor's coil is energized, how much resistance should be measured between terminal L1 and terminal T1?

• zero ohms
• 50-3000 ohms
• 5000-6000 ohms
• infinite

Which of the following overload devices is not affected by ambient temperature?

• Which of the following overload devices is not affected by ambient temperature?
• magnetic
• bimetal
• none of these

If a normally operating motor draws 75 amps on startup, it will most likely draw ___ amps when running.

• 15
• 25
• 35
• 12