Corrected from:
i700 servo inverter V01.05.06.9665
Response of the new version:
Thermal contacts (normally closed contacts) (TKO) can be used to detect over-temperatures in the motor.
The i700 behaves as described in the corresponding hardware manual. The resistance value of the lower grid point of the user-specifc temperature sensor characteristic can be parameterised to < 122 ohms without erroneously triggering an error message.
When using a TKO, the notes for the safe electrical isolation must be observed!
What happens? When using a thermal contact (normally closed contacts) (TKO) instead of a continuous temperature sensor (KTY, PT1000) to detect over temperatures in the motor, the 'Open circuit - temperature sensor' error message is activated when the normally-closed contact is closed.
Due to this function restriction TKO cannot be used.
When does the problem occur? The problem occurs immediately when the TKO is connected and the temperature sensor characteristic is set accordingly.
Which products are affected? i700 servo inverter
Short-term measures/recommendations: Virtually none.
Only theoretically and if absolutely necessary possible: Connect an ohmic resistor in series with the thermal contact and adapt the temperature sensor characteristic accordingly so that there will be a 'permissible' resistance value available (in the range of a continuous temperature sensor) when the normally closed contact is closed.
Evaluation: In most cases, continuous KTY temperature sensors are used for servo motors.
Thermal contacts in the motor winding are rather to be found in existing systems which are to be operated with new controllers as part of retrofittings.
The above-described short-time remedy may be applied until the next i700 firmware release will be available.
Important: Double basic insulation is required. See AKB article:
Temperature sensor (PT1000, KTY, PTC, TCO): Protection against electric shock requires a reinforced insulation for safe isolation
