Controls Midterm Flashcards
What’s a bi metal
Two metals bonded together with different coefficients of thermal expansion
Internally powered controller is
Hot water tank
What normal state should a high limit control be in
Normally closed
What is a low limit control for
Interrupt the system operation if the condition drops below the desired value
What is differential
A sustained deviation between the actual control point and the set point under stable conditions
What type of control system is relays and contractors
Electromechanical
Relays have both NO and NC contacts
True
What device is used to protect end use devices
Overcurrent device
When is an OFC used
When a reciprocating compressor has an oil pump
How is a compressor short cycling reduced
Delay on make timer
What does DTC stand for
Dual temperature control
A timer motor in a time clock is always powered
True
What must be done to a mercury thermostat to maintain setpoint accuracy
Be level
Contactors you can
Repair
What does an OFC protect
Compressor running without oil
