Thermal motor protection
The motors can be equipped on request with silicon sensors (KTY84), “PTC thermistors”, resistance thermometers PT100 or with a bimetal temperature sensor. In connection with the current limitation of the assigned SIMOREG converter reliable motor protection is reached. The thermistor sensors are connected to terminals in the terminal box and can be analyzed in the SIMOREG DC MASTER 6RA70 basic unit.
If the control unit is activated by an overshoot of the admissible overtemperature, the armature and the field circuit have to be shut down immediately under continuance of the separate cooling.
If a warning is needed besides the shut down of the motors when monitoring via PTC sensors, 2 thermistor sensors have to be installed. This option can be analyzed in the SIMOREG DC MASTER 6RA70 with the option "terminal expansion" (K00), or with the temperature monitoring relay 3RS10. The warning is normally displayed 10 to 15 K under the shut down temperature.
I 2 t - Monitoring
In connection with theI2t-monitoring of the SIMOREG DC MASTER converters, the motor can be protected from inadmissible loading. TheI2t-monitoring describes roughly the thermal image of the motor (no full motor protection).
For activating theI2t-monitoring, the thermal equivalent time constant from the following diagram is needed. The thermal equivalent time constant depends on the maximum over-current.
Thermal equivalent time constantTtherm
Motors from frame size 180 can be ordered with earthing brushes (refer to Catalog DA 12 · 2004, chapter " Selection and Ordering - Options") or can be retrofitted (on request).
Earthing brushes avoid bearing damages, which arise from wave voltages caused by the system (e.g. unequal capacity distribution on operation at non-earthed converters).
A monitoring of the brush length (limit) is possible as follows:
Motors of up to inclusive frame size 450 are equipped with a micro switch for each brush-holder stud. The normally closed contacts are connected in series, the signal is potential-free. The connection is made at 2 terminals of the auxiliary terminal strip in the motor terminal box. The evaluation can be either made in the SIMOREG DC MASTER 6RA70 with the motor interface or separately.
Micro switch connection
Motors of frame sizes 500 and 630 are equipped with a signalling brush for each brush-holder stud. The alarm signal is potentially fixed. The connection is made at 4 terminals of the auxiliary terminal strip in the motor terminal box. Both polarities have to be analyzed separately. For evaluation, the monitor KM01 of Schunk Kohlenstofftechnik GmbH, Wettenberg can be used.
The cables between device and machine have to be installed short-circuit and earth-fault proof. Intermediate terminals, e.g. in a control cabinet, have to be equipped with a cover marked with a flash arrow.
Signalling brush connection
Bearing temperature and bearing condition
For monitoring the bearing temperature two resistance thermometers PT100 can be installed in machines from frame size 180. The connection is made at the auxiliary terminal in the motor terminal box.
The bearing condition can be monitored at machines from frame size 180 with the SPM method. For this measuring nipples are mounted on the drive end and the non-drive end of the motor.
The monitoring is made via a stationary monitoring device (alarm box) or a mobile device. The SPM alarm box supplies a logic signal (break or make), circuit technology loading max. 125 V AC, 50 VA.
Air flow monitoring
For monitoring the cooling air flow the flow control switch vent-captor type 3201.03 or 3201.51 is available for machines with top-mounted fan or cooler.
DThe evaluation of the vent-captor type 3201.03 can be made in the SIMOREG DC MASTER 6RA70 with motor interface. For type 3201.51 the evaluation is made separately.