What is the term for the maximum reverse voltage that can be applied to a diode
PIV
A DC motor connected to a drive is overheating despite running within its rated current.
What could be the cause?
Improper commutation due to worn brushes.
What is significant about the operating characteristics of a ‘current-limiting’ fuse?
It opens in less than 0.5 of a cycle under a short circuit current.
Work is to begin on a high-voltage power system that must first be de-energized.
Who is responsible for ensuring that the part of the system being worked on is made safe?
The person in charge.
What is the reason for the installation of a filter within a rectifying system?
It smooths out the DC pulsating voltage.
The purpose of the condenser in an air conditioner unit is to:
remove the heat from the coolant to convert it from a gas to a liquid.
What does the term ‘high-limit cycling’ refer to?
Gas valve opening & closing because of the high-limit switch contacts opening & closing, due to plenum temperature
With which type of device should a motor be equipped with, when automatic restarting would create a hazard?
Low voltage protection.
Generally, as the rotor speed of an induction motor increases, then the slip
decreases & the torque decreases.
Michael adjusts this field rheostat for a synchronous motor, until the lowest line current is achieved.
What is the PF of this motor?
Unity
a wound rotor induction motor (WRIM), complete with rotor, slip rings and rotor resistors.
When running at maximum speed, contacts C3 (closest to motor) are closed.
Do Generators in parallel share the KVAR load by adjusting the effort of their prime mover.
No
When troubleshooting a generator, what is accomplished when we flash the field
Establishes residual magnetism.
What effect should the fire alarm system have on the HVAC system
It must shut-down the HVAC system.
A split phase motor has
A starting and running winding.
The output voltage of a stand-alone 3-phase generator is less than required for a particular application.
What should be done to increase the output voltage?
Increase the field current.
Generators in parallel share the KW load by adjusting their governors.
True
How do you change the direction of rotation of a split-phase, single-phase motor.
Reverse the connections to the START winding.
What are three critical items for high voltage overcurrent protection that must be checked?
Type, rating & interrupting capacity of devices.
What is a variance, in the electrical industry?
Permission to deviate from the required practice.
Which of the following is a common problem in cathodic protection systems?
Stray current corrosion
When commissioning a three-phase motor, how do you verify the correct direction of rotation?
Perform a bump test by momentarily energizing the motor.
You are troubleshooting an alternator because it does not build voltage.
Which could be a possible cause?
Open field winding
A VFD, which controls a 50hp motor, shuts down due to the drive overheating.
The motor is not overloaded and the drive seems to be operating normally.
What would you do to correct the problem?
Inspect & test the cooling fan in the drive, then replace the defective fan.
