Hi,

My generators get a signal to start up from an ATS whenever a mains failure occurs. Pretty simple setup. The total available load for each gene is just about 20-25% of its rated capacity. When i simulate a mains failure, the unit starts up and takes on the load...and then within few seconds trips on -kvar !!

I'm basically not an electrical guy...and honestly don't know much...but i fail to understand how a single standby generator which isn't connected to the grid (ATS) can trip on negative kvar.
The generators are fitted with MICS-Telys controls. Voltage and Hz are steady.

I should also point out that 90% of the load is high mast tower lights. Each tower has 8 halogens on it. When the switch occurs, all the ELCB's of the towers trip. I have tried resetting the ELCB's allowing 10-15 secs delay between each. If the ELCB's hold, the generator trips. I'm having this problem with all the 12 generators.

If any additional information is required, plz do let me know. Thnx.

 

Karma6... What did the MICS-Telys tell you were the pre-fault, during-fault, and post-fault parameters, specifically: kV; kA; kVA; kW; kVAr; pf; Hz; fuel-flow; and any other data considered pertinent enough to solve the problem!! >Hi,

Regards. Phil Corso

 

well , the generator can trip on negative VAR if you have a capacitive load in the system. This has happened in industrial installations where they have a power factor correcting capacitors. on loss of grid the induction motors trip leaving the large uncompensated capacitor bank online. when the backup generator starts it trips on reverse VAR. something similar is happening here.

are you sure that you use halogen lamps and not high discharge arc lamps . arc lamps have poor power factor and have power factor regulating equipment. does your site have pf regulating equipment?

elcb can trip for a variety of reasons other than fault. unbalanced load is an example. what is the rating of the elcb and where is it used in the system. without looking at at least the single line diagram it is difficult to diagnose the problem.

i do not think that you have a fault in your system( i am taking a guess that under grid supply the elcb does not trip and all ) . the problem is sudden unbalanced loading and presence of capacitive loads in the system.

Hope this helps a little way.

 

Thnx for your reply. Will look into the points you have mentioned. Unfortunately, the tower lights are looked after AFL (air field lighting) and they aren't being very co-operative. My dept has no access onto the apron. So I'm just going to have to figure a way of getting my hands on their diagrams.

Thanks anyway.

 

> Thnx for your reply. Will look into the
> points you have mentioned.

glad to be of some help , and write back on what you have found out and fixed .