CH 11 Test (book Ch 10) Flashcards
What is the simplest form of overload protection?
Fuse
What are the contacts of the contactor composed of to resist sticking?
Silver and Cadmium
The contacts of the contactor make a complete circuit when the contactor is _____, allowing voltage to flow to the controlled load.
Energized
A _____ is an electric device that protects a load from a high amp draw by breaking a set of contacts.
Overload
A load that is purely resistive in nature with no coils to cause induction is called a resistive _____ or what kind of load?
Load // Non-inductive (resistive) Load
What are the two basic groups that overloads can be divided into?
Line break and Pilot duty
Describe the two types of loads that a contactor can control.
Inductive load- a motor, which has a higher ampere draw on startup than while running
Resistive (non-inductive) Load- a resistance heater, which has a constant ampere draw
True or False. Contactors, make or break a set of contacts that control the voltage applied to some load in cooling systems.
True
True or False. Coil characteristics depend on the type of wire, but not the manner in which it is wound.
False (depends on type of wire and manner in which it is wound)
True or False. Contactors are rated by the ampere draw they can carry.
True
True or False. Contacts are made of silver and cadmium, which resist sticking.
True
True or False. The contactor contacts must be in good condition to ensure that the proper voltage reaches the load.
True
Fuses cannot be used to protect wires and non inductive loads, but they do provide adequate protection for inductive loads.
False (can be used to protect wires and non inductive loads)
True or False. Relays cannot be used to open and close a control circuit.
False
A contactor is used to control an electric load and a control zone.
True
The diagnosis of a faulty contactor encompasses three sections of a contractor. What are they?
Coil, contacts, and mechanical linkage
The chemical composition of contacts is such that they operate at cool temperatures of up to _____ percent of their current carrying capacity
125%
A _____ overload breaks the power to a motor.
Line break
One of the most common types of line voltage overload is a _____ mounted between two contacts.
Metal disc (bimetal line break overload)
Name five devices used in the HVAC industry that can be controlled by relay.
Indoor fan motor, condenser fan motor, damper motor, starting capacitor, and control lockouts
What is a in internal compressor overload?
Most common line break overload used for small central residential systems. It is a small device inserted into the motor windings which senses current draw and temperature.
