PowerQualityDoctor
Senior Member
- Location
- Israel
pct/il2007/000892
Power factor question
- Thread starter puckman
- Start date
- Status
pct/il2007/000892
ATSman
ATSman
- Location
- San Francisco Bay Area
- Occupation
- Electrical Engineer/ Electrical Testing & Controls
Leading PF
Leading PF
I was on a job as a rep for the ATS manufacturer along with the reps for the genset and UPS. Contractor was cutting over a second MSB and we were to each go thru the senarios during an outage and explain what should happen and what to do if things go wrong.
I noticed that the KW reading on the MX350 controller (GE Zenith) was negative, the KVA & KVARs were both positive values. First thing comes to mind is a reversed CT or reversed sec connection. I believe all 3 currents were reading positive but I am not positive:grin: The power factor was 0.8 leading. After discussion with the gen & UPS guys we concluded that the leading PF was caused by the lightly loaded UPS: 60KVA out of a total of 400kva (15%.) Total load #'s were:
-96 KW
123 KVA
77 KVAR
+0.8 PF leading
on top of this, the UPS load is the majority of the total building load which we believe is causing the high current THD of 16%.
Question: Can the leading PF cause the negative KW reading and if so, why?
I can't see that it would because that would mean we were co-generating and that was not the case. GE is checking into it, also.
Any input would be appreciated
I will also post this in another category.
Tony
Leading PF
I was on a job as a rep for the ATS manufacturer along with the reps for the genset and UPS. Contractor was cutting over a second MSB and we were to each go thru the senarios during an outage and explain what should happen and what to do if things go wrong.
I noticed that the KW reading on the MX350 controller (GE Zenith) was negative, the KVA & KVARs were both positive values. First thing comes to mind is a reversed CT or reversed sec connection. I believe all 3 currents were reading positive but I am not positive:grin: The power factor was 0.8 leading. After discussion with the gen & UPS guys we concluded that the leading PF was caused by the lightly loaded UPS: 60KVA out of a total of 400kva (15%.) Total load #'s were:
-96 KW
123 KVA
77 KVAR
+0.8 PF leading
on top of this, the UPS load is the majority of the total building load which we believe is causing the high current THD of 16%.
Question: Can the leading PF cause the negative KW reading and if so, why?
I can't see that it would because that would mean we were co-generating and that was not the case. GE is checking into it, also.
Any input would be appreciated
I will also post this in another category.
Tony
PowerQualityDoctor
Senior Member
- Location
- Israel
Negative kW means one of two:
1. Energy goes back to the network.
2. Wrong connection or setup.
Normally UPS cannot accept regenerative energy, so I guess it is some way of wrong connection.
There is another option which is that your meter is confused due to the high amount of harmonics.
1. Energy goes back to the network.
2. Wrong connection or setup.
Normally UPS cannot accept regenerative energy, so I guess it is some way of wrong connection.
There is another option which is that your meter is confused due to the high amount of harmonics.
- Status