WEG S Series - Alarm and Trip Temperatures; Temperature Limits for the Windings

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11866576 Installation, Operation and Maintenance Manual – Synchronous Motors – S Line – Brushless – Horizontal l 23
NOTE
Resistance temperature detectors (RTD)
allow the monitoring via the absolute
temperature informed through their
instantaneous resistance value. With this
information the relay, which can be
programmed for alarm and trip according to
pre-defined values, is able to perform the
temperature reading.
4.5.1.2 Temperature limits for the windings
The temperature of the hottest spot of the winding must
be kept below the limit of the insulation thermal class. The
total temperature is obtained by the sum of the ambient
temperature and the temperature rise (T), plus the
difference between the average temperature of the
winding and the hottest spot of the winding.
The ambient temperature must not exceed 40 °C, in
accordance with NBR IEC60034-1 standard. Above this
temperature, the working conditions are considered
special and the motor specific documentation must be
consulted.
Table 4.4 shows the numerical values and the
composition of the acceptable temperature of the hottest
spot on the winding.
Table 4.4: Insulation class
Insulation class (ºC) F h
Ambient temperature 40 40
T = temperature rise (temperature measurement
method by resistance variation)
105 125
Difference between the hottest point and the average
temperature
10 15
Total: temperature of the hottest point 155 180
A
TTENTION
If the motor operates with temperatures in
the windings above the limit values of the
insulation thermal class, the lifespan of the
insulation and, consequently, of the motor,
will be significantly reduced, or it may even
result in the motor burnout.
4.5.1.3 Alarm and trip temperatures
The motor alarm and trip temperatures must be set at the
lowest possible value. These temperatures can be
determined based on the factory tests or through the
motor operating temperature. The alarm temperature can
be set 10º C above the motor operating temperature at full
load, always considering the highest ambient temperature
on site. The adjusted trip temperatures must not exceed
the maximum acceptable temperatures for the stator
winding insulation class and for the bearings (considering
the lubrication type and system), according to Table 4.5.
Table 4.5: Maximum temperature settings
Maximum temperature settings for
protections (ºC)
Alarm Tripping
Winding class F 130 155
Winding class H 155 180
Bearings 110 120
A
TTENTION
T
he alarm and trip values may be determined
as a result of experience, but they must not
exceed the values indicated in Table 4.5.
A
TTENTION
The motor protection devices are listed in the
WEG drawing - Connection diagram.
Not using these devices is the sole
responsibility of the user and, in case of
damage to the motor, it will void the
warranty.