Figure 3-9 Thermal Overload Protection - Siemens MICROMASTER 430 Operating Instructions Manual

Issue 10/06
External motor thermal overload protection
When operated below rated speed, the cooling effect of fans fitted to the motor
shaft is reduced. Consequentially, most motors require de-rating for continuous
operation at low frequencies. To ensure that the motors are protected against
overheating under these conditions, a PTC temperature sensor must be fitted to
the motor and connected to the inverter control terminals.
5 V
574 Ω
Kl. 14
A
PTC/
KTY
Kl. 15
PTC-Auslöseschwelle = 4 V

Figure 3-9 Thermal overload protection

With PTC sensor (P0601 = 1)
If the PTC in the motor is connected to the MICROMASTER 430 control terminals
14 (PTCA) and 15 (PTCB) and the PTC function enabled by setting P0601 = 1,
then the MICROMASTER 430 will operate as normal providing the resistance at
the terminals remains below approximately 1500 Ω. If this value is exceeded, the
inverter indicates a warning A0511 and then a fault F0011. The actual resistance
value at which this occurs will not be less than 1000 Ω, and not more than 2000 Ω.
With KTY84 sensor (P0601 = 2)
The KTY84 has to be connected so that the diode is forward biased; that is the
anode is connected to terminal 14 (PTCA) and the cathode to terminal 15 (PTCB).
If the temperature monitoring function is enabled by setting P0601 = 2, the
temperature of the sensor (and therefore the motor windings) is written to
parameter r0035. The threshold motor temperature can now be set using
parameter P0604 (default setting 130 °C).
Connection failure
If the connection to the PTC or KTY84 sensor becomes open circuit or short circuit,
a fault will be indicated, and by default the drive will trip.
MICROMASTER 430 Operating Instructions
6SE6400-5AE00-0BP0
D
PTC-Charakteristik für 1LG/1LA-Motoren
http://nicontrols.com
3 Commissioning
KTY84-Charakteristik
59