Discuss the use of taps in autotransformer starters.
What will be an ideal response?
Many autotransformer starters contain taps that can be set for 50 percent, 65 percent, or 80 percent of the line voltage. Reducing the voltage applied to the motor not only reduces the amount of in-rush current, but also reduces the motor torque. If 50 percent of the normal voltage is connected to the motor, the in-rush current will drop to 50 percent also. This will produce a torque that is 25 percent of the value when full voltage is connected to the motor. If the motor torque is insufficient to start the load when the 50 percent tap is used, the 65 percent or 80 percent taps are available.
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Determine the minimum number of 10-ampere, 120-volt rated general illumination branch-circuits required for an office space of 762m2 in area. Hint: the unit load for this office space is 39 VA/m2.
What will be an ideal response?
A Division ___________________ area is one in which the hazardous material is likely to be present.
Fill in the blank(s) with the appropriate word(s).
Why are relay coils and contacts not shown in the same place on a schematic diagram?
What will be an ideal response?
The cells on most electronic air cleaners can be cleaned:
A) By spraying them in place with an air conditioning coil cleaner. B) By spraying them in place using a solvent that is certified to be high in volatile organic compounds. C) In the dishwasher. D) With a fine grit emery cloth.