Blinking Lights - Pole Top Cap Bank set 1 span from Line Regulators

[Manindemand]

On 13.8 kv circuit we've had customer complaints of blinking lights. After visually inspecting the circuit the only unusual condition was a 3 phase pole top capacitor bank (with Beckwith M-2501B Autodaptive control) installed one pole span downstream of 3 single phase line regulators.

I'm wondering if the regulator and cap bank configuration might be causing a buck and boost condition due to the close proximity and both use voltage sensing for control.

Could this setup be causing the voltage dips and spikes or is this a typical configuration?

Thank you for your assistance.

Manindemand

 

[bacon4life]

It seems kind of strange to have two devices both trying to control the voltage at the same point. If they were not coordinated they could be interfering with each other. Has there been an usualy high number of operations on either device?

 

[Manindemand]

Sorry to take so long getting back. You know how it is, busy.

I don't have the software or IR cable to be able to read data.

Budget is tight, so, I was just hoping someone had also experienced this type of problem to help us decide whether to change the cap bank controls to a different type/config.

We still have a recording meter at the station, so, I'm thinking about taking the cap bank off line and watch our recorder readings to see if blinks go away.

REAL MEN LOVE JESUS!

 

[wareagle]

Your term "voltage dips and spikes" is not the same as blinking to me. Blinking signifies an interruption of power. Is that what you mean?

 

[davidbeach]

wareagle, you can easily see as a flicker if not a blink in both fluorescent and incandescent lighting sags of 5-6 cycles that get down to 70% or less of nominal voltage. Working as a utility protection engineer I have seen many blinks/flickers that I can tie to specific events and know the duration and magnitude of the sag.

 

[wareagle]

David
You are right. I am familiar with the term "flicker" and I usually associate it with occurrences such as motor starting.
I was just trying to clear up the terminology for me.

 

[Dumbo2929]

This is a long shot, but you may have a ferroresonance condition from the close proximity of the capacitor and regulators, which can cause abnormally high voltages. These voltages may be causing the capacitor to open, or regulator to buck down. I had one customer with such an issue, under light load conditions. Are the regulators connected in delta or wye?

It is characterized by the sudden onset of very high sustained overvoltages along with high levels of harmonic distortion. Ferroresonance has been known to be responsible for equipment damage and equipment protection malfunctions.

 

[Manindemand]

bacon4life - sorry I overlooked your question - No, no trips on station feeder or on OCRs.

wareagle and davidbeach - blinking is probably not the best word to describe. Flicker is more accurate. Some early records show momentary dips down to 90 VAC at customers meter.

Dumbo2929 - sounds like you nailed it. Each regulator is connected wye. The records also show overvoltage spikes as you describe.

Some problem descriptions include:
1.)Computer backup power supplies turning on an off as sags occur.
2.)Computers rebooting (with no UPS).
3.)Ceiling fans can be heard humming louder and softer as they speed up and slow down - while customers try go to sleep.
4.)Lights dimming and brightening.

For some reason the major problems just stopped around 11-18-07...beats me?

I'll upload a few records for you to view. I guess we get one file per post so I'll follow with 2 more posts.

Thank you all for your help. I'm sending our engineers a link to this thread in hopes it will assist them.

Manindemand

REAL MEN LOVE JESUS!

 

[Manindemand]

Here's another file.

I don't know how those add links got into my previous post!





REAL MEN LOVE JESUS!

 

[Manindemand]

And the last file.

REAL MEN LOVE JESUS!

 

[johnnyball]

After reviewing the voltage and current trends from the recorder, this looks very similar to a problem we had several months ago, with the same type customer complaints. If this is confined to just one phase, I would consider looking at the voltage regulator for that phase. The contacts on the automatic tapchanger could be in need of servicing. Arcing contacts will cause this problem.

 

[KVX10]

We experienced similar events as johnnyball. The frustrating thing was that we didn't suspect the regulator as it was only 2 years old. We operated the tapchanger manually and came across our problem. (If you are on site with the regulator you will probably hear it as well as see it on you evaluation equipment.)