Power Quality Issues
Power Quality Issues
(OP)
We are facing issues with our 90kVA UPS which is more than 25 years old. We connected Fluke 435 to the output of the inverter which recorded multiple events of Dips and Swells. We shifted the Fluke 435 to 480VAC UPS input side and recorded more than 6000 transients events on the fluke within 24 hours. These transients were between phase A and C and their magnitude was 100V above the normal voltage. UPS output was not effected and no event was recorded in the DCS. Before these transients there were several events recorded by DCS for the Static switch transfer although in real there was no transfer and system was operating normal. Please advise what to investigate.






RE: Power Quality Issues
A UPS that old probably doesn't have a pure sinewave output voltage but contains lots of PWM or PWM residues, which the 435 doesn't interpret very well.
If there's no other problem than the 435 showing funny events and results, then just leave it.
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
RE: Power Quality Issues
"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington
RE: Power Quality Issues
More than likely, a significant number of them would originate at the facility itself. That's certainly true with the 6,000 transients in 24 hours, but I think it also applies to the 60-80 range too.
RE: Power Quality Issues
"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington
RE: Power Quality Issues
435 was connected just to see the input voltage because we had swells and dips event recorded by the DCS on the output of the UPS (without any trip, only alarms.
A 480V switchgear is feeding multiple MCCs and one of those MCC in turns feed the UPS. Another MCC on the same switchgear feeds the Central Airconditioning system for the building which is probably around 100 tons. Do you think that can have impact because of its frequent switching because the outside temp. here is nearly 50 deg. Celcius now a days.
RE: Power Quality Issues
Best is to hook up current clamps on the Air Conditioning system and keep the connection to the 480 V. Then trig on transients and see if they coincide with heavy inrush or starting currents to the AC system.
If there is a corelation, you have to either live with it or find a fix for it.
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.