Electricity Level 2, Section 11
Solid-state relays normally have control voltages of
3V to 32V
Which of the following can provide motor overload protection but have the disadvantage of being nonrenewable?
Dual-element or time-delay fuses
Increasing the armature spring force in a relay will result in
Higher drop-out values
When making connections to reverse the rotation of a motor,
L1 is connected to motor terminal T3, and L3 is connected to motor terminal T1
Which of the following has the advantage of being resistant to shock and vibration and is commonly used for the I/O track of a programmable controller?
Solid-state relay
On magnetic contactors, which contacts are said to be normally open (NO)?
Those that are apart when the relay is de-energized
Low-voltage remote control switching relays use
a split coil
The panel for a low-voltage lighting control system enclosure should be mounted
at eye level between two studs
An electromagnetic device that can be used to multiply the switching function of a pilot device is a
control relay
If contactor action is dependent on current flow, the contactor is described as
electrically held
Lighting contactors are rated for
high inrush currents
The two classifications of overload relays are thermal and
magnetic
If low-voltage and high-voltage cables must be placed in parallel runs, they should be separated by at least 6" in order to protect the low-voltage conductors from
noise
Which of the following is a probable cause of relay-controlled equipment failing to start when the contactor is closed?
one contact not closing
A motor overload relay consists of a current-sensing unit and mechanism activated by the sensing unit that
opens the motor circuit
Melting alloy and metallic overload relays are designed to
react to changes in the motor load current
Mechanically held relays and contractors are often used because
they are quiter than electrically held devices
The lubrication of a motor at prescribed intervals can be accomplished using a
timing relay
