GEH-5304A
15
2. When intended for use on a power supply other than “A”, “C”, “D”, “E” or “K”, the motor wil l
be identified as follows:
M / N F - V - H - L
Where M = A digit indicating total pulses per cycle
N = A digit indicating contr olled pulses per cycle
F = Free wh eeling (this letter appears only if free wh eeling is used)
V = Thr ee digits indicating nominal line-to-line AC voltage to the rectifier
H = Two digits indicating input frequency in hertz
L = One, two or thr ee 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
con nection s 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 th e same con nection. (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 pro perly at t ached.
F. M otor F iel d Heati ng
MOTOR FIELD HOUSING – Unless specifically ordered, mo tors are NOT cap abl e
of continuous standstill excitation at rated field current. When t he mot or is shut
down for more than 30 minutes, one of the following options must be used:
1. De-energiz e t he fields comp letely.
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 pr ovide 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
con ditions 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.