Arc Flash Labels on 15KV Switchgear Lineup

[levans]

I am doing an arc flash study and the plant has a 6900VAC Magnablast switchgear lineup of multiple breakers. Do I figure the arc flash level and PPE for each breaker door or do I label each door based on the worst case for the lineup (probably main bus breaker)?

 

[zog]

I am doing an arc flash study and the plant has a 6900VAC Magnablast switchgear lineup of multiple breakers. Do I figure the arc flash level and PPE for each breaker door or do I label each door based on the worst case for the lineup (probably main bus breaker)?

What do you mean for each breaker door? Not following you. You need to calulate the Ei for each piece of equipment. You need to do several calulations for each point with diffeent fault currents to determines which fault current and clearing time combonation gives you the highest Ei, (or "worst case" as I assume you are asking about).

Sounds like you should hire someone to do this for you.

 

[ron]

Typically we provide a label indicating the worst case operating mode for IE. We locate it near the client's equipment identification nameplate.
Often this is indicative of the IE of the main bus. If the main breaker (if present) is in an isolated section, then we put an additional label indicating the line side IE if it is worse than the bus.

 

[RoberteFuhr]

I am doing an arc flash study and the plant has a 6900VAC Magnablast switchgear lineup of multiple breakers. Do I figure the arc flash level and PPE for each breaker door or do I label each door based on the worst case for the lineup (probably main bus breaker)?

We will perform the calculations for the Main bus and create one label. The energy level of at the main bus will be dependent upon the main relay settings and the time that it takes to trip.

The exceptions to this are (1) The line side of the main breaker will usually have a higher energy level due to the settings of the upstream provtective device. We then create a line side label for the Main Breaker Cubicle. (2) You can create labels for the rear cable connection compartments because these energy levels will usually be lower and are based upon the feeder relay and not the main relay. (3) If you have a bus tie breaker, be careful. You may have twice the energy level as the main bus because both line and load side of the tie breaker bus is energized and a potential arc flash energy source.