UPS / EMI?....Problem

[Ahr35181]

I?ve had a problem mentioned to me at work & wondered if any UPS or EMI specialists out there could shed some light. May I apologise for the lack of detail?.

We have a 230V UPS which supplies a process control computer & VDU?s which are fed via some unit which steps the voltage down (approximately 24V I?m informed).

When a portable fan or a 230V VDU are plugged into a 230V 13A socket outlet block (from which the computer & ELV VDU?s are supplied) the ELV VDU?s go blank for a few seconds & then come back on. Apparently no loss of supply is seen by the 230V supplied process computer.

If it?s any help, all equipment mentioned are contained in one panel which is well bonded with 6mm2 earth straps & an independent 6mm2 earth to the switch room earth bar.

Thanks,

Alan

 

[rbulsara]

You did not provide the size (kva) of the UPS units and load connected to it.

It appears that the starting current of the fan motor momentarily dips the voltage hence the effect.

Suggest not to plug in any non-critical items (which this fan seems to be) on output side of an UPS (critical bus).

This appears not related to EMI.