GE Industrial Control Systems GEEP-124-I Copyright 1997,1998 The General Electric Company, USA
18
GEEP-124-I Horizontal Induction Motor
WPI, Antifriction Bearing
The foundation should be constructed in
accordance with the requirements in the section
entitled “Foundation” on page 7. If the unit has been
properly aligned, the amplitude of the vibration of
the installed motor should be as stated in the above
table. If vibration amplitudes are significantly
greater than these values, the instruction referenced
above should be reviewed. Misalignment is the most
probable cause of excessive vibration. Other possible
causes are “soft” shim packs under one or more feet,
loose foot bolts or an inadequate foundation.
Contributions to vibration from the driven equipment
should not be overlooked.
Do not operate the machine with excessive
vibration. If the cause cannot be found and
corrected, contact the nearest General Electric office.
Frequency of starts and load
inertia
When a motor starts, it must accelerate the
rotational inertia of its own rotor and that of the
driven equipment from standstill to full speed.
Accordingly, it must transfer and store a larger
amount of energy into the rotating parts in a short
time. An equal amount of energy is dissipated in the
rotor windings in the same short period of time.
During the starting period, current in the
windings are several times the rated value. This
causes heating of the windings at a significantly
greater rate than occurs at full-speed operation.
Also, because magnetic forces are proportional to the
square of the current, forces on the winding end
turns are many times greater than the normal
condition.
For the above reasons, the frequency of starts and
the magnitude of rotational inertia of the connected load,
must be limited for squirrel-cage induction and synchronous
motors. The motors covered by this Instruction Book (unless
otherwise stated in the, sales contract), are suitable for
accelerating the rotational inertia of the driven equipment in
accordance with Standard MG 1-21.42. The motors are
suitable for the following frequency of starts.
1.
With the motor initially at ambient temperature,
two starts in succession, coasting to rest between starts.
2.
With the motor initially at a temperature not
exceeding its rated temperature, one start.
It is recommended that the total number of starts
made in the life of the machine be controlled, with an effort
to minimizing them, since the life of the machine is affected
by the total number of starts.
Wound rotor induction motors have the capability to
accelerate high inertia loads with limited stator current
through the use of external resistance inserted in the rotor
circuit. The motor characteristic is changed by adjusting the
resistance. Most of the energy dissipated in the rotor circuit
during the acceleration is dissipated in the resistor external
to the motor.
Oil level
Sleeve bearing machines are furnished with an oil
level gauge in each bearing housing. Refer to the
Parts
Identification Instruction
for this model to locate the oil
level gauge. The gauges are either bulls eye type, with a
circular glass window, or column type.
With the bulls eye type gauge, the centerline of the
gauge indicates maximum oil level and the bottom of the
gauge indicates minimum oil level
.
DLCGEEP-124-I/000, Approved, 2016-11-11, CampinasDM
