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Siemens D 83.1 · 2016
2
Motors with Explosion Protection
LOHER CHEMSTAR and VARIO 1PS1 motor series
General information
■
Technical specifications
(continued)
Electrical design
The insulation system of the 1PS1 motor series is suitable for line
voltages up to 690 V. The connection system (terminal box,
terminals) is also designed for this rated voltage.
The explosion-proof motors are equipped with 6 terminals. They
can thus be operated in star or delta. If a voltage variant with
dual voltage e.g. 400 V
/690 VY is selected, the rated data of
both voltage levels will be stamped on the rating plate.
The motors in the 1PS1 range are made with an insulation
system which corresponds to thermal class 155 °C. Utilization at
rated operation corresponds to thermal class 130 °C.
Operation on a frequency converter
The general use of high-quality insulation systems enable
operation on a frequency converter.
The permissible speed and torque range is stamped on an
additional rating plate.
For operation on a frequency converter, the motor with explosion
protection must be fitted with PTC thermistors (or Pt100 as an
option for LOHER VARIO). These are installed in the stator
winding and, in combination with a certified trip unit (EU type
examination certificate), they perform sole motor protection in
the case of converter operation. Motor circuit breakers can be
dispensed with.For motors with type of protection Ex n, the
standard requires the motor manufacturer to perform a type test
together with the original converter or to provide comparable
evidence that guarantees that the explosion protection limits are
observed.
Acceptance testing of explosion-proof motors of
type of protection Ex nA
For dimensioning and for acceptance testing, with regard to the
heat rise of all parts of the machine, the most unfavorable value is
used. Motors of the 1PS1 series are certified for temperature class
T3. None of the components, even those inside the enclosure
(e.g. rotor cage winding), are permitted to exceed a temperature
of 200 °C. The winding temperature is limited by the thermal class
(e.g. 155 (F)). The reason for the above-mentioned initial test on
the original converter is normally to establish compliance with the
temperature limits for the motor with type of protection Ex nA.
Special cases "blocked shaft" and "starting":
Type of protection Ex nA excludes these two special cases.
Limit temperatures are permitted here that do not take into
account the temperature class. Even though "blocked shaft" and
"starting" are excluded, a motor of the type of protection Ex nA
is not permitted to be implemented for heavy starting. These
motors are only permitted to be operated on soft-starting
devices under the following conditions:
•
The soft-starting device has been function-tested by the
German Federal Testing Laboratory
•
A motor circuit breaker must be provided as a minimum of
protection
•
The duty type does not give rise to expectations of a
significant increase in temperature as a result of the starting
procedure
(e.g. pump drives with a low moment of inertia)
Voltage tolerances
The motors are suitable for operation with voltage and frequency
tolerances according to EN 60034-1.
In addition, tests are to be performed to ensure that the
permissible temperature limits for the outer surface of the
explosion-proof enclosure according to EN 60079-1 are not
exceeded during continuous operations at the voltage limits
(± 10%).
The motors in the 1PS1 range in this catalog are certified for T3.
The maximum permitted surface temperature is 200 °C.
© Siemens AG 2016