GE GEH-5304A manual Connections, Protective Devices, Motor Field Heating, Thermostats

GEH-5304A

2.When intended for use on a power supply other than “A”, “C”, “D”, “E” or “K”, the motor will be identified as follows:

			M / N F - V - H - L
Where	M	=	A digit indicating total pulses per cycle
	N	=	A digit indicating controlled pulses per cycle
	F	=	Free wheeling (this letter appears only if free wheeling is used)
	V	=	Three digits indicating nominal line-to-line AC voltage to the rectifier
	H	=	Two digits indicating input frequency in hertz

L= One, two or three digits indicating the series inductance in millihenries (may

be zero) to be added externally to the motor armature circuit inductance.

D.Connections

Terminal connections should be checked against the connection diagram shipped with the machine. Bolted connections must be tight. All exposed connections in the conduit box must be insulated. When more than one terminal is marked with the same identification, they should be joined in the same connection. (Refer to Table 6 for identification of wiring leads.)

E.Protective Devices

Make certain that all protective devices (overspeed devices, bearing tempera- ture relays, etc.) are connected and function properly. Also, make certain that all coupling guards, shaft protectors, grounding connectors, covers and other safety devices are properly attached.

F.Motor Field Heating

MOTOR FIELD HOUSING – Unless specifically ord ered, motors are NOT capable of continuous standstill excitation at rated field current. When the motor is shut down for more than 30 minutes, one of the following options must be used:

1. De-energize the fields completely.

2.Use field economy relays to limit the field current to a maximum of 50% of the nameplate rating.

3.When applicable, fields may remain fully energized if the motor ventilation system (blower or customer duct) remains in operation.

G.Thermostats

The thermostat is a device that may be used in alarm or protective relay circuits within rating limits shown in Table 5. It is not intended to limit motor loading or provide normal insulation life. When supplied, it is mounted to a commutating coil which is the only accessible part of the armature circuit. Since factors such as shaft speed, ventilation (blower or shaft fan), current ripple (SCR phase-back) and short-time overload affect the temperature relationship between armature and commutating field, complete protection from all conditions resulting from over-temperature is not possible. The device is intended to guard against complete loss of normal ventilation air, high ambient temperature, and prolonged operation of self-ventilated motors at very low speeds.

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