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25 Cards in this Set
- Front
- Back
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In order from the source name the 4 comments in a power circuit. |
Disconnect, over current, contactors, OLR. |
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A magnetic motor starter contains which of the two? (Contactor, OLR, Disconnect switch, fuses, elements or all power circuit components) |
Contactors, OLR. |
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The holding contact in a 3 wire control circuit is located in the? (Fused disconnect, motor contactor, OLR or start/stop push button enclosure) |
Motor contactor. |
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A 3 wire control circuit requires "blank" remote device conductors. |
3 |
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A standard 2 wire control circuit does not provide what type of protection? |
Low voltage protection. |
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The N.C. Contact of an off delay timed relay set at 20 sec will operate how when energized? |
Open when the coil is energized and closed 20sec after the coil is de-energized. |
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A forward reverse magnetic starter requires "blank" 3 pole contactors and "blank" 3 pole OLR's |
2 , 1 |
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A start/stop only runs the motor when the push button is held on. What is the problem most likely to be? |
The maintain contact. |
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The rated FLA of an AC induction motor is used for what sizing? |
Is used to size the OLR heater elements |
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Which devices are considered loads in a motor control circuit and therefore must be placed in parallel with each other? |
Indicating pilot lamps Contactor coils Timed relay coils |
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NEMA mags have what ratings? |
H.P. And voltage rated. |
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The overload relay contained in a 3 phase mag contains? |
3 OL elements and 3 N.C. Contacts. |
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Which power circuit component provides both start and stop functions? |
3 main mag contacts |
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The 3 fuses or 3 pole circuit breaker in the power circuit of a 3 phase motor provides? |
Line to line or line to ground fault conditions. |
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When changing the voltage of a dual motor, which components must be changed? (Assume the control circuit is fed from the power circuit lines.) |
OLR heater elements, contactor coil and fuses. |
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Control circuit voltage is often fed from the motors starter line voltage then reduced with a control transformer. The primary lines of the transformer should be connected where? |
Between the fuses and main contacts. |
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A magnetic motor starter is only used for 3 phase AC motors? (T,F) |
F |
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Manual motor starters can be used for motors up to 15 H.P. |
F |
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Motors using manual motor starter do not require over load protection? |
F |
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A combination magnetic motor starter enclosure incorporates a safety disconnect, fuses, magnetic motor contactor, and an overload relay? T/F |
T |
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A zero speed switch is simply an automatic device that senses rotation just like a limit switch senses travel. |
T |
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"Plugging" refers to a control circuit that ensures a motor shaft is at a slow enough speed to safely reverse its rotational direction. T/F |
F |
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A 3 phase motor can be quickly decelerated by reversing the rotating magnetic field but only until the rotor stops. The control circuit may use a zero speed switch or timed relay. T/F |
T |
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The control circuit for an unattended basement sump pump using a float switch should be provided with low voltage protection. T/F |
F |
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N.C.H.O refers to a time delay relay, T/F |
F |
