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encoder isolation question

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Hi
I have a question regarding some encoder I want to use. I did not work before with encoders so I do not know much about their construction.
I have this encoder , namely 05.2400.1122.0360
https://www.conrad.com/ce/en/product/198493/Kuebler-05240012220360-Incremental-Encoder-Type-2400

It will measure the speed of an induction machine. I want to have all parameters isolated . I don't know if this encoder provides galvanic isolation (>=3kV) between the motor and the logic signals it provides.
Can anyone know if I should use some optocouplers for the logic signals provided by the encoder or I can use them directly and feed them to the MCU (directly meaning without isolation)
 

Hi,

it is very unlikely that an encoder provides 3kV isolation.

You need to define the 3kV. Is it continous 3kV AC RMS? Is it DC? Is it a mixture?
Or is it just the test-voltage?
You need functional isolation or safety isolation?

Klaus
 

3kV AC RMS 1 min/50Hz isolation test; safety isolation
The encoder will be used in an inverter ; the control part i want to be isolated from the HV side
So most likely I have to use optocouplers?
 

Hi,

I like to use POF in this case.

Klaus
 

Don't see why you want 3 kV isolation for an encoder with grounded case. 500 V would be appropriate if necessary at all.
 

My sole motivation is the fact that the other electrical quantities that I measure (voltages, currents) are isolated using some chips which are rated at 3kV isolation.
In fact I don't have any knowledges about how to choose the right isolation voltage I need given the aplication. I need isolation for : electrical safety (the conntrol part of the inverter will be touched by humans) and to improve measurement performances.
 

Isolation is required for any measurements connecting to the (HV) power circuit, an encoder doesn't so the signals must not necessary be isolated. Isolation might be still wanted to improve noise suppression, as it's e.g. used for field busses. Encoder inputs of a vector drive will usually not provide isolation and rely on proper grounding of the encoder case and shielded cables.
 
Fit the encoder inside a fully enclosed plastic box using nylon screws, and use an insulated shaft coupling.
 

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