Thermal Motor Model; Ptc Sensor; Kty84 Sensor - Siemens MICROMASTER 440 Parameter Manual

Parameter Description
5 V
T
ADC
PTC
KTY

Thermal motor model:

The data, required for the thermal motor model, is estimated from the rating plate data entered during the
quick commissioning. This data permits reliable, stable operation for standard Siemens motors. If required,
parameter changes must be made for motors from third-party manufacturers. We always recommend that
an automatic motor data identification run is made after quick commissioning so that the electrical
equivalent circuit diagram data can be determined. This allows a more precise calculation of the losses
which occur in the motor which has a positive impact on the accuracy of the thermal motor model.

PTC sensor:

A PTC temperature sensor (Positive-Temperature-Characteristic) is a resistor with a positive temperature
characteristic which, at normal temperatures, has a low resistance value ( 50-100 Ohm). Normally, three
PTC temperature sensors are connected in series in the motor (depending on the motor manufacturer), thus
producing a "cold resistance value" ranging from 150 to 300 Ohm. PTC temperature sensors are also
frequently referred to as cold conductors.
However, at a certain threshold temperature, the resistance rises rapidly. The threshold temperature is
selected by the motor manufacturer in such a way that it corresponds to the nominal temperature value of
the motor insulation. This allows the change in the resistance value to be deployed to protect the motor, as
the PTCs are embedded in the motor windings. PTC temperature sensors are not suitable for measuring
temperature.
When the PTC is connected to the control terminals 14 and 15 of the MM4 and the selection motor
temperature sensor has been activated by the setting P0601 = 1 (PTC sensor), the PTC temperature sensor
then protects the motor by means of the trip device in the MM4.
Should the resistance value of 2000 Ohm be exceeded, the inverter displays error F0011 (motor
overheating).
If the resistance value is below 100 Ohm, the error F0015 (no motor temperature signal) is then output.
This protects the motor from overheating and also from a sensor wire breakage.
The motor is additionally monitored by the thermal motor model in the inverter, thus providing a redundant
system for monitoring the motor.

KTY84 sensor:

The sensor KTY84 is basically a semi-conductor thermo-sensor (diode), the resistance value of which
varies from some 500 Ohm at 0°C to 2600 Ohm at 300°C. It has a positive temperature coefficient and, in
contrast to the PTCs, has an almost linear temperature characteristic. The resistor behaviour is comparable
to that of a measuring resistor with a very high temperature coefficient.
Note the following when connecting the polarity. Connect the sensor so that the diode is polarized in the
operative direction. That means that the anode needs to be connected to terminal 14 = PTC A (+) and the
cathode to terminal 15 = PTC B (-).
If the temperature monitoring function is activated with the setting P0601 = 2, the temperature of the sensor
(thus that of the motor windings) is then written to parameter r0035.
The motor overheating warning threshold needs to be assigned with parameter P0604 (the works setting is
130°C). This warning threshold depends on the motors thermal class. Also refer to the table below in this
context.
70
Fault
F0015
P0601 = 2
= 4 s
1
No sensor
Signal
0
loss
PTC
1
detection
KTY
2
P0601
Equivalent
circuit data
Power dissipation
P
V,mot
&
1
0
r0035
ϑ
V
1
0
Thermal
r0631
P0604
motor
r0632
model
r0633
MICROMASTER 440
Issue 01/06
r0052
Bit13
Motor
≥
1
temp.
reaction
P0610
Parameter List
6SE6400-5BB00-0BP0