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Can we use soft starters Altistart ATS22 or ATS48 or ATS480 or ATS130 to prime an electric heater appliance?

The heater represents a resistive or slightly inductive load. The utilization category is AC-1
The operation of Altistart (ATS) for the heater application is not validated. There is almost no risk of ATS damage, only the functionality cannot be guaranteed.
First, ATS requires more inductive load (cos phi of induction motor is around 0.8).
Second, the rise of the current when thyristors get conductive is normally limited by motor inductance. Here in the case of the heater, the rise of the current di/dt is much higher (especially during the "starting") and it is unpleasant for thyristor operation. The limit rise di/dt is characteristic of thyristor and depends on the voltage and the load inductance and resistance. If di/dt exceeds critical value thyristor can be damaged.
Third, ATS functionality regarding acceleration, torque control, and end of starting can fail or give incorrect signalization. The controlled stop does not make sense as well.

Conclusion: ATS use for heaters is fully under the customer's responsibility.