Flickering in Power System

Hello adrian

Is that <" Voltage dip / flickering about one second exist in our power system"> caused by internal load, is does that Voltage Dip arrive from outside the plant = from the High Voltage line to your local transformer/s?

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Kind Regards....

Voltage dip comes from external source (medium voltage size , 20 KV), and affect to our load.

cheer

adrian; does this happen more on windy days? sound like a tree branch hitting the hi-

voltage power line, should be self trimming perry

Hello again, adrian

Your out-of-balance current is probably a reflection through your local plant transformer of a severe Voltage drop on a single one of the supply phases from your Electricity provider.

If you increased the size of your local transformer, perhaps by 10% or 15%, the reflection may not be as noticeable, because there would be more iron in the magnetic circuit to absorb the transient fault.

This is an expensive transformer increase, should you choose to make it.

If your Electricity provider often has this type of fault, you are going to get the reflected imbalance, and associated neutral current, as your local system tries to cope with the HT fault in the supply.

Without having your full plant and equipment details, along with complete schematics, I cannot properly advise you to alter the ACB Protection relay settings, because the settings are both a safety and Insurance issue, and "remote control via CR4" is not a good idea - If I was actually on-site then the advice may be quite different.

The settings would normally be specified in the initial Works Installation Manual, and they are set at what appears to be a reasonable amount, for protection of persons and equipment at the Works.

Can you establish which phase of the High Tension Supply line gets the Voltage drop fault?

If so, and it is always the same phase, either there is a faulty insulator/transformer or other equipment on that phase, branch of tree intermittently touching that phase, or lightning strike to that phase only, or some local interference - in all these cases, you should advise the Electrical Engineer of that Distribution Network, so that remedial action/s may be made.

Advise further, as needed.

Kind Regards....