Problem With Nokian Pf Controller N-12

Hi Signode;

In some cases if your load increases beyond the PFC Unit capacity, then the PFC Unit may automatically trip, which will require additional capacitor KVAs.

PFC Unit size = 1400KVA No. of Steps = 12 Stepping sequence = ? Main Switch Board Rating = 3500A Current Loading = 500 - 700A

Rought calculations: If L-L = 415V, 1400KVA/415=3 373.49A There hasn't been any additional load to trip the unit, and the unit is near sized to the main switch board rating, that I don't think this may have anything to do with the plant loading. I have had installation and program setting problems but hope these may assist you in anyway. I had good support from our PFC Unit supplier.

Safety First

Always consult the manufacture for their support.

Before carrying out all these checks, do ensure the unit is switched off with LOTO applied. Wear required PPEs/ARC Flash PPEs.

Some Areas To Look At

1. Check CT Operation;

You may want to check the PFC Unit's CT, to ensure they are not faulty, and are feeding the correct measured current (A) to the unit's controller. Check CT connections for lose terminal screws. For Electrical Safety – shut down the unit and LOTO.

2. Check THD (Total Harmonic Distortion) of your plant based on recognized standards; You PFC Unit controller should be able to give you the measured TDH.

Shut Down the PFC Unit and Do Maintenance Checks as per the PFC Unit manual, try ask the unit's supplier: For Electrical Safety – shut down the unit and LOTO.

3. Check for lose/damaged connections on contactors, cap-banks, reactors, and terminal blocks. For Electrical Safety – shut down the unit and LOTO.

Inspect contactors and contactor coils for possible coil damages. Some times contactor main switching poles may become damaged due to long operations. For Electrical Safety – shut down the unit and LOTO.

4. Controller Operation Check:

If you have the unit's manual, go through it and see how you can do factory reset. Before doing factory reset, make note of the present controller settings such as CT Ration, THD, Voltage, Current, Temperature, Stepping Sequence, and others so as to manual set those operating parameters back.

When you do factory reset, make note of the default stepping sequence, and listen to the sets if the cap-banks are switching in as per the factory stepping sequence. This is to ensure the stepping sequence of the controller is working. When I was doing the Controller Operational Check on our PFC Unit, I did it with no plant load and later with plant load

Try other controller operation checks which should be outlined in the manual to possible identify any controller failures which may exists that may have an effect the controllers operation. If controller program is failing you may need to replace the controller with possibly an exact type.

Please consult the supplier.

Thanks my friend for that detailed answering