HEIDENHAIN encoders ERM 280 speed encoder

[sammmy_s]

We havea 100kw AC motor with HEIDENHAIN encoders ERM 280speed encoder.

The motor works ok up to 500 rpm under closed loop control.

Anything above 500 it trips on A508 encoder fault.

The encoder reader head and the disc are they a matching pair?

Thanks for any advice.

[Al_The_Man]

The encoder receiver and scale are generally matched, as the infra red sensor has a graticule grating in front of it that is the same resolution as the scale itself, but slightly skewed.
If you are lucky it may be just that the scale and head requires cleaning with De-natured alcohol.
Al.

[Al_The_Man]

I see the ERM200 series are Magnetoresistive not optical.
Not sure in that case whether the heads are interchangeable?
Al.

[sammmy_s]

Thanks for the information. The motor went out for a bearing replacement and since then have not been able to run it at a high speed without the fault. I don't believe it is a wiring problem because it works at a low speed.
Could it be a balance problem on the motor?