Individual Motors and Motor Banks - Section 28 Flashcards
Is section 28 supplemental?
Yes, it amends the general sections of the CEC.
What kind of equipment typically requires low voltage protection?
Pinching cutting or crushing equipment;
Anything liable to create a hazard upon automatic startup.
If using a manual motor starter, what typically should it be rated in?
Horsepower rated.
Why must conductors terminating to a hot motor require a certain length?
So that the conductor can act as a heat sink down it’s length.
Under what circumstance may a motor’s supply conductors be sized on 90 º?
On a class A motor, when using 90 degree wire.
Why must each motor have a manual disconnecting means?
So that anyone doing service can ensure the power is cut off.
Where can FLA estimates be found in the CEC?
Tables 44 (3Φ), 45 (1Φ) and D2 (DC).
When sizing conductors for a continuous motor, what multiplier must be used on the FLA for the largest motor?
1.25.
What table is used for sizing overcurrent devices for motors?
Table 29.
If a service factor is not marked, what is it’s assumed service factor multiplier?
1.15.
What is a special rating, typically linked to hermetic refrigerant compressors?
Locked rotor current.
When using a part winding or a star delta starter, what must be done special for sizing the motor supply conductors?
There are six supply wires so the ampacity must be increased accordingly (0.8).
When sizing a wound rotor motor’s resistor wires, what temperature insulation must be used?
90 Degrees.
When sizing overcurrents for mutiple motors, what must be done?
Calculate OC for the largest motor, then add the FLAs of the rest;
If started simultanaeously, then treat all as one large motor, then use Table 29.
When sizing conductors for non continuous motors, what table must be used?
Table 27.
