ATSman
ATSman
- Location
- San Francisco Bay Area
- Occupation
- Electrical Engineer/ Electrical Testing & Controls
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
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