Siemens CGZ - Manual (Page 16)

- 15 -
Maintenance
Temperature
Electrical apparatus operating under normal
conditions becomes quite warm. Although some
places may feel hot to the touch, the unit may be
within limits. If checking total temperature by winding
resistance or imbedded detector (RTD), the total
temperature should not exceed the following:
When operating at full load:
Class of Insulation System
B F H
Temp. by
Resistance
All HP
120°C
(248°F)
145°C
(293°F)
165°C
(329°F)
1500HP
or less 130°C
(266°F)
155°C
(311°F)
180°C
(356°F)
Over
1500HP
-Under
7000V
125°C
(257°F)
150°C
(302°F)
175°C
(347°F)
Temp. by
Embedded
Detector
Over
1500HP
-Over
7000 V
120°C
(248°F)
145°C
(293°F)
165°C
(329°F)
When operating at 1.15 service factor load:
Class of Insulation System
B F H
Temp. by
Resistance
All HP
130°C
(266°F)
155°C
(311°F)
175°C
(347°F)
1500HP
or less
140°C
(284°F)
165°C
(329°F)
190°C
(373°F)
Over
1500HP
-Under
7000V
135°C
(275°F)
160°C
(320°F)
185°C
(365°F)
Temp. by
Embedded
Detector
Over
1500HP
-Over
7000 V
130°C
(266°F)
155°C
(311°F)
175°C
(347°F)
These temperatures represent the maximum
temperature for each class of insulation and include a
40°C ambient temperature. Operation above these
temperatures will result in reduced insulation life.
Vibration
Most problems can be detected when inspected
visually. Check for;
1. Loose or missing parts, such as fan blades, nuts,
bolts, screws, couplings, etc.
2. Accumulation of dirt on fan or rotor.
3. Associated
equipment - Disconnect equipment to
determine where the vibration is being generated.
4. Foundation construction - Base, grouting and
associated equipment supporting drives must be
in good condition. Vibration can be amplified by
weak construction. Vibration of base just below
motor feet should not exceed 25% of motor
vibration.
5. History - When was vibration first noted? Was
there a change in loading and/or duty of
equipment? Has ambient vibration changed?
More important than the actual vibration is the
vibration change over a period of time.
Corrective Maintenance
Two factors that require corrective maintenance are
electrical failure or mechanical failure. The first sign
of electrical failure is usually low insulation
resistance. Mechanical failures are usually preceded
by excessive bearing noise or heat.
Low Insulation Resistance
Factors that usually cause low insulation readings
are:
1. Dirty windings (oil, dust, grease, salt, etc.).
2. Excessive
moisture.
3. Mechanically damaged insulation.
4. Heat
deterioration
Dirty winding can be cleaned and moist windings
dried; however, items 3 and 4 require extensive
repairs by a certified service center.
CAUTION
Flying dirt, dust or other particles.
May cause eye injury.
Wear safety glasses and dust mask when using
compressed air.
Cleaning
Clean the outside of the motor regularly. Actual
conditions existing around the motor dictate the
frequency of cleaning operations. Use the following
procedures as they apply.
1. Wipe off dust, dirt, oil, water, etc., from external
surfaces of the motor.
2. Remove dirt, dust, or other debris from ventilating
air inlets and exhausts. Do not operate motor
with air passages blocked or restricted.