Thermal Motor Protection And Overload Responses - Siemens MICROMASTER 440 Operating Instructions Manual

Issue 10/06
3.21

Thermal motor protection and overload responses

Parameter range:
Warnings
Faults
Function chart number:
MICROMASTER 440 has a completely new integrated concept for thermal motor
protection. There are numerous possibilities of effectively protecting the motor but
at the same time ensuring high motor utilization. The basic philosophy of this
innovative concept is to detect critical thermal states, output warnings and initiate
the appropriate responses. By responding to critical states it is possible to operate
the drive at the thermal power limit and to avoid, under all circumstances, an
immediate shutdown (where the drive inverter is tripped).
Features
The protective concept (refer to Fig. 3-93) distinguishes itself as a result of the
following individual features:
Protection is effective without using any temperature sensor (P0601 = 0). The
temperatures of various locations in the motor are indirectly determined using a
temperature model.
It is possible to evaluate temperature sensors. This has the advantage that after
a line supply failure, precise initial temperatures are immediately available. Both
PTC sensors (P0601 = 1) as well as KTY84 sensors (P0601 = 2) can be
connected and evaluated (refer to Section 3.21.2).
When using a KTY84 sensor, the drive inverter can be parameterized so that a
sensor wire breakage or short-circuit F0015 is detected and the system
automatically changes-over to the temperature model. This means that the drive
inverter is not shut down (tripped) and operation can continue.
Selectable temperature warning thresholds P0604 (default: 130 °C) for
operation with the temperature model or KTY84 sensor. The drive inverter is
shut down or the current reduced depending on P0610 for a value of P0604
+10%.
Selectable responses P0610 which are to be initiated when the warning
threshold is exceeded in order to prevent an overload condition.
The motor protection has been designed to be completely independent of the
drive inverter protection. Warning thresholds and responses for drive inverter
protection must be separately parameterized.
Various data sets are taken into account in the model. The model is separately
calculated for each data set so that when changing-over between various
motors the cooling of the presently non-active (fed) motors are taken into
account.
MICROMASTER 440 Operating Instructions
6SE6400-5AW00-0BP0
P0601 – P0640
P0344
P0350 – P0360
r0035
A0511
F0011, F0015
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3 Functions
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