Eliminated from:
Inverter Drives 8400 TopLine from firmware version 12.01.00.00
Behaviour of the new version?
The monitoring function does not respond anymore if resistance values are very low.
Which products are affected?
Inverter Drives 8400 TopLine up to firmware version 12.00.00.00
What happens?
The monitoring function of the thermal detector at the encoder interfaces responds although a resistance value of approximately 0Ohms can be measured. The error message says 'Sd6: Error thermal detector resolver' or 'Sd12: Error thermal detector multi-encoder'.
The current motor temperature is displayed with C63/1=255°.
When does the problem occur?
If a resistance value approximate to 0Ohms is pending at the KTY interface while the monitoring function is activated (C583/5 or C583/5=1..6).
This is for instance the case if a TCO thermal contact for which only the cable resistance and contact resistance take effect in the closed state, is evaluated instead of a KTY.
Diagnostics options?
The behaviour can be simulated with a short wire jumper at X7 pin 8 + 9 or X8 pin 7+8.
Short-term measures/recommendations?
Connect TCO in series connection with a 1..10Ohm resistance, or deactivate thermal sensor monitoring C583/5=0 or C583/6=0.
For the display of the unexpected motor temperature of C53/1=255° in the event of an error, no remedy is provided.
Evaluation:
The error status occurs sporadically and reduces the machine availability. Typically, from an ambient temperature of approximately 10°C and a cable length of of approximately 10m, the resistance value is high enough to avoid the response of the monitoring function when the TCO is closed.
