Specifications

Electrical Installation
Siemens Building Technologies, Inc. 41
Motor Overload Protection
WARNING:
The SED2 is capable of providing internal motor overload
protection in accordance with UL508C, Section 42. Accurately
configure motor parameters for the motor overload protection
to operate correctly. See Motor I
2
t Temperature Reaction
parameter (P0610); I
2
t is On by default.
Motor overload protection also can be provided using an
external PTC temperature-thermistor sensor (disabled by
default via Motor Temperature Sensor parameter (P0601)).
During operation below nominal speed, the cooling effect of the fans
mounted to the motor shaft is reduced. Therefore, most motors require
de-rating if operated continuously at low frequencies. To ensure that
motors are protected from overheating under these conditions, mount a
PTC temperature-thermistor sensor to the motor and connect it to the
control terminals of the SED2.
NOTE: To enable the switch-off function with a PTC temperature-
thermistor sensor, set Motor Temperature Sensor parameter
(P0601) to 1 for PTC temperature-thermistor sensor. Use a
shielded cable to connect the PTC temperature-thermistor
sensor.
14
15
SED2
CONTROL
TERMINALS
VFD0031R1
Figure 26. External Motor Overload Protection.