phase unbalance capacitors

[streeta]

On site we have Sag and Ball mill's. In the starter pannels we have 2x 122.7uF capacitors in circuit for phase out of ballance adjustment. We have just recently lost 2 sets of capacitors, we believe this is due to power fluctations, Power outages and surges. Is there any way we can protect these (another capacitor in line or something). Any information would be greatful.
Please if you may need anymore information contact me on gstreet@bglgh.com

Thanks
Greg

 

[jbartos]

Suggestion: Several options exist:
1. Higher voltage rated capacitors
2. Incorporation resistors or inductors in series with capacitors on individual basis
3. Individual capacitor branch protection
4. Apply power line conditioners instead
5. Balance the load more evenly
6. Etc.

 

[busbar]

This may take some time.

Are they 3ø motors fed from a utility-provided 3ø source?

How many motors of what horsepower? Induction [squirrel-cage] or synchronous?

What voltage? Grounded-wye or delta service? What frequency?

Are the capacitors connected symmetrically? What type of overcurrent protection do they have?

Are you certain they are not provided for power-factor correction?

Are the capacitors switched by other than the motors’ single magnetic starter?

Please detail how you determined you “lost 2 sets” of capacitors.