Electrical engineering quiz questions and answers on electromagnetic motor starters, overload relay, auxiliary control contacts, two-wire control, motor control ladder diagrams, and hand-off-Automatic (H-O-A) control of a 3-phase AC motor,
Electromagnetic Motor Starters Questions
The _______ auxiliary contacts can also be used to ________ the 3-pole electromagnetic motor-starter of a second motor when two motors cannot be operated simultaneously.
A) NC; lock-in
B) NO; lockout
C) NC; lockout
D) NO; lock-in
In the basic 3-wire control circuit of a 3-phase AC motor using a 3-pole electromagnetic motor -starter, two individual PB switches are required:
The _________ PB switch serves to initiate a run condition of the motor and must be wired in parallel with a set of _________ auxiliary contacts on the motor-starter to seal in the start action.
A) NO Start; NC
B) NC Start; NO
C) NC Start; NC
D) NO Start; NO
If the NC Stop PB switch is held open (depressed), activating (closing) the NO Start PB switch will not initiate the control function: the circuit is disabled.
This method of control lockout (referred to as _________ switching) is often used to prevent a 3-phase AC motor from being started during a process cycle.
A) none of the answers
The use of momentary-type selector or pushbutton switches in a ladder diagram is normally limited to _________ control.
Low- or no-voltage _________ is characteristic of 2-wire control.
B) none of the answers
When a 3-wire control consists of two PB switches wired in series, the _______ momentary PB switch is used as the interrupt or stop switch.
The _______ momentary PB switch is used as the initiate or start switch.
A) NC; NC
B) NO; NO
C) NC; NO
D) NO; NC
The term ______________ describes any control operation in which a function, motion, or operation can be caused either to occur (lock-in) or to be prevented from occurring (lock-out), simultaneously with another function, motion, or operation.
In the basic 3-wire control circuit of a 3-phase AC induction motor that uses a full-voltage motor -starter, two individual PB switches are required.
The two individual PB switches must be wired in _______.
Continuous control-voltage or control power is normally applied to the __________ PB switch, which serves to interrupt the start or run condition of the motor.
The __________ PB switch, which serves to initiate a run condition of the motor, must be wired in parallel with a set of __________ auxiliary contacts on the motor-starter to seal in the start action.
A) series; NO Start; NC Stop; NO
B) series; NC Stop; NO Start; NO
C) series; NC Stop; NO Start; NC
D) parallel; NC Stop; NO Start; NO
E) parallel; NO Start; NC Stop; NO
F) parallel; NC Stop; NO Start; NC
_____________ control of a 3-phase AC induction motor, by means of an electromagnetic motor -starter, uses momentary switches with either pushbutton- or selector-type operators.
In troubleshooting a motor control circuit, ___________ measurements, with the power on, are normally the preferred method.
A) Either resistance or voltage
The mechanical closing of the power contacts in a 3-phase full-voltage motor starter is accomplished by mechanical linkage and a concentrated electromagnetic field.
The field is produced by a coil contained in the motor-starter solenoid.
When two motors are controlled with a 3-position selector switch, the control or run status of the two motors are interlocked with the single switch.
If both motors are to be OFF in the center position of the switch, then both sets of contacts should be at-rest in their ________ configuration.
________ is commanded to start when the switch is turned to the left position. __________ is commanded to start when the switch is turned to the right position.
A) NO; Motor 2; Motor 1
B) NC; Motor 2; Motor 1
C) NC; Motor 1; Motor 2
D) NO; Motor 1; Motor 2
When two or more sets of contacts are controlled (opened or closed) simultaneously by a 2-position, maintain-type selector switch, the switch is further described as a ________ switch.
C) Either sequential or slider
Regarding grounded or ungrounded circuit conductors, individual wires in a control circuit must color-coded.
They must be further identified with an effective wire-numbering system.
The two side rails of the ladder diagram are referred to as the control-power busses.
The load side of the fuse in the ______ circuit conductor is identified as wire #1.
The ______ circuit conductor (circuit common) is identified as wire #2.
A) grounded; ungrounded
B) ungrounded; ungrounded
C) ungrounded; grounded
D) none of the answers
The term interlock describes any control operation in which a function, motion, or operation can be caused either to occur ________ or to be prevented from occurring _________, simultaneously with another function, motion, or operation.
A) lock-in; lock-in
B) lock-out; lock-in
C) lock-out; lock-out
D) lock-in; lock-out
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