Skogsgurra
Electrical
I have been asked about measuring power fed to grinding motors. Piece of cake, I said. And it was, until I got the specs.
PWM, induction motor, variable frequency. Normal power transducers do not work well with variable frequency and they do not like EMI from the motor cables.
I Yokogawa has a decent transducer. But cost is in the 40 - 50 000 USD range and accuracy is way better than needed.
I have always used the drive's internal power representation for this kind of measurements but it seems to be too complicated for the grinding guys. And I can understand that. Different parameters and different outputs. On top of that, the scale factors differ between different brands of drives.
Does anyone know a decent power transducer that works over the 10 - 100 Hz range, can work with heavy EMI and powers up to around 100 kW? Accuracy needs to be at least +/-2 % of full scale. Price around a tenth of the Yokogawa device.
Gunnar Englund
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Half full - Half empty? I don't mind. It's what in it that counts.
PWM, induction motor, variable frequency. Normal power transducers do not work well with variable frequency and they do not like EMI from the motor cables.
I Yokogawa has a decent transducer. But cost is in the 40 - 50 000 USD range and accuracy is way better than needed.
I have always used the drive's internal power representation for this kind of measurements but it seems to be too complicated for the grinding guys. And I can understand that. Different parameters and different outputs. On top of that, the scale factors differ between different brands of drives.
Does anyone know a decent power transducer that works over the 10 - 100 Hz range, can work with heavy EMI and powers up to around 100 kW? Accuracy needs to be at least +/-2 % of full scale. Price around a tenth of the Yokogawa device.
Gunnar Englund
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
