Voltage Dip preventor

A properly sized fuse, circuit breaker or switchgear protection trip relay (both current and trip curve) to isolate your system supplying the fault current from the fault itself quickly to limit the short circuit current duration. Ideally this should be as close as possible to the fault, additionally in most cases this "protection discrimination" should already be employed (whether it has been sized correctly or not is another story).

Exactly what sort of dips are you talking about, as any phase to phase or phase to ground fault is potentially going to cause a large fault current to flow and hence a dip in the voltage (as the generation cannot produce the same voltage when the power requirements jump one or more orders of magnitude)?

Can you provide more information please including more on this voltage dip, the type of fault, duration, problems experienced you are trying to solve, existing protection scheme, country, etc. This is not the sort of question that can be answered by saying "just add a big inductor".

If the fault is on your site, you should look at how you manage that fault or In-rush current.

If it is on a neighbouring site which is the way I am reading your question, apart from contacting your utility supplier and getting them to chase the faulty party you will have to look at how to protect your system internally.

You might want to look at a UPS for the equipment that is sensitive to these dips.

Regards,
Sapper.

There are several approaches you can take, each having their own pros and cons. It would be good to have the following information:-

1. Do you have a captive power plant / cogen at your facility ? If so, what % of generation do you export ?

2. What is the effect of the voltage dip ? What are the specific problems that you face and at what voltage dip (level, duration) ?

3. What kind of load do you have in your plant ? How much of it is critical ? Are there any alternate supplies available to these critical loads ? Are they separated on different busses so that specific solution like fast bus transfer / UPS can be provided for the same.

Any other information that you can provide will be useful to review and revert.

Amit.

Dear Friends,

Ours is a big interconnected system having generations at different locations at 50-100 km between each power stations having generations 300MW to 1300MW in different stations. when any fault occurs near to the bus of any stations, a voltage dip ,30% or below occurs-which sometimes is cleared after about 500-1000ms. This voltage dip causes auxiliary failure and unit(s) suffer outage.Will the choice of higher %Z of Generator-transformers or Auto-transformers(interconnection some units at132KV level and 220KV level) be helpful in this respect? or should we go for faster tripping of the faulty feeders--even if the fault is in 2nd. zone?