If you are using a Passive Filter with the Process drives, There are 3 pairs of contacts that you can short out as an option.
The purpose of these contacts is to reduce the capacitive reactive power when the VSD is in RDY or with low load.
Under no-load conditions (standby operation), the drive current is negligible. So the main current drawn in standby mode at the input of the harmonic filter is a purely capacitive reactive current that flows through the capacitor of the harmonic filter. This reactive current component typically corresponds to approx. 20-25% of the specified nominal harmonic filter current (depending on the respective harmonic filter type).
For Example, You might see 25A which corresponds to approximately 25% of a 99A rated passive filter. The power factor of the drive is very low in this condition and changes, depending on the load.
To reduce this reactive current and avoid grid overcompensation, it is recommended to switch off this reactive current in standby mode. This reactive current can be disconnected by a contactor that opens the connection between terminals X3 and X4.
A commercial AC3 contactor can be used for disconnection. The AC3 contactor power must be at least 50% of the filter's nominal power. This contactor can be connected and disconnected, depending on the performance of the drive, up to a maximum load of 30%.
The ATV630 drive can manage the contactor using one of its relays. It will keep the contactor open when the current is less than 10% of the drive's rated current.
You might have some additional questions, Which have been answered below :
- Will we damage the filter if we leave it in the “reactive current” condition for prolonged periods of time?
No risk of damage to the filter. In any case, the capacitor reactive current will be flowing in the filter, due to the capacitors of the filter itself, and it can hold this current for sure.
We are planning to leave the links between terminals X3 and X4 open all of the time.
- Will this disable the filter entirely?
Passive filters are an LC filter, and X3/X4 will disconnect the capacitor only. So, the inductance will stay on, so you can see it as a line choke, and will reduce the THDi a little bit, but not as much as the complete filter.
- Will the VFD operate normally if we remove the links between terminals X3 and X4?
Yes, the VSD will operate normally, there is no risk for the VSD.
Released for: Schneider Electric Ireland
