User Manual

Functions

5.3 Motor protection / intrinsic device protection (3RW40 only)

SIRIUS 3RW30 / 3RW40

Manual, 10/2010, 535199502000 DS 03

Recovery time (thermistor motor protection)

If the thermistor motor protection is tripped, the soft starter cannot be restarted until the

sensor installed in the motor has cooled down. The recovery time varies according to the

temperature state of the sensor.

5.3.2 Intrinsic device protection (3RW40 only)

Thyristor protection (thermal)

SIRIUS 3RW40 soft starters are equipped with integrated intrinsic device protection to

prevent thermal overloading of the thyristors.

This is achieved on the one hand by means of current measuring transformers in the three

phases and on the other, by measuring the temperature with temperature sensors on the

thyristor's heat sink.

If the fixed, internally set trip value is exceeded, the soft starter is automatically

disconnected.

Recovery time (intrinsic device protection)

If the intrinsic device protection is tripped, the soft starter cannot be restarted until a recovery

time of at least 30 seconds has elapsed upon overload of the thyristors and at least

60 seconds upon overload of the bypasses.

Thyristor protection (short-circuit)

SITOR semiconductor fuses must be connected upstream to protect the thyristors against

short-circuits (e.g. in case of cable damage or an interturn fault in the motor; refer to chapter

Soft starter assembly with type of c

oordination 2 (Page 65)). For the fuse selection tables,

refer to chapt

er Technical data (Page 127).

Protection against voltage failure (in the event of a fault)

If the control supply voltage fails during a trip, the current tripping state of the thermal

intrinsic device protection model and the current recovery time are stored in the soft starter.

When the control supply voltage is restored, the current tripping state of the thermal intrinsic

device protection prior to the power failure are likewise automatically restored.

NOTICE

If the control voltage is disconnected during operation (e.g. in "automatic mode"), the starter

is not protected against voltage failure. You must wait five minutes between two starts to

ensure that the motor protection and the intrinsic device protection are working correctly.