Winding protection systems

For the protection of the motor winding three-phase induction, against overtemperatures caused, for example, by overload or by use with only two phases, the motor can be equipped with the following protections:

Bimetallic Thermo-protector:

Consists of two protectors connected in series. The contact is normally closed, opens when the winding temperature reaches the limit of danger to the insulation system.

PTC Temperature Sensors (Thermistors):

Consists of 3 sensors connected in series and inserted in the windings.
Once you reach the setting temperature, PTC resistance changes rapidly.
The PTC must be connected to a control relay (supplied on request).

PT 100 temperature resistors (for sizes from 132 and up):

The strength of these devices change with shifts in the temperature of the windings. They are particularly suitable for continuous control of the winding temperature. For perfect control requires at least two sets of PT 100.
The PT 100 must be connected to the appropriate control device (supplied only on request).
The PTC and PT100 are means of protection suitable for motors working not in continuous service or in special conditions.
For example: short-term services with increased powers, long starting times, large number of starts and stops, poor cooling, high ambient temperature.
The motors controlled by variable frequency (inverter) are always supplied with PTC Thermistors.
These are two Thermistors terminals for connection located inside the main terminal box.
A request can be placed on a separate terminal box of the motor housing.