Question for the group about Tampa Electric's Schedule GSD power factor provisions. Client has a 1.2MW data center with UPS systems and they're getting PF penalties even though their main service PF meter shows 0.94. TECO claims they're measuring 0.81 PF and billing accordingly. The UPS systems have built-in PF correction showing 0.98+ on their displays. Is TECO measuring upstream of the UPS or is there something about UPS power factor that I'm missing? The penalties are running $4,200/month on Schedule GSD-1.
TECO Schedule GSD demand-side power factor measurement
Kevin, UPS systems can be tricky for power factor measurement. Many UPS units correct their output power factor but not necessarily their input power factor, especially under partial loads. The utility is measuring at the service entrance (input to UPS) while your client is probably looking at UPS output readings. Also, if they have multiple UPS units with different load levels, the input PF can vary significantly between units. What type and vintage of UPS equipment are we talking about?
Randy's spot on about input vs output PF. I had a similar case with Dominion in Richmond - customer had Liebert UPS systems from around 2015-2018 vintage. Those units have excellent output PF correction but input PF can drop to 0.75-0.80 when loaded below 50%. Data centers often run UPS systems at 30-40% load for redundancy, which puts them right in that poor input PF range. The solution was either load-sharing between UPS units or upgrading to newer units with better input PF correction.
They have four Eaton 9395 UPS units, about 300kW each, installed in 2019. Each is running around 35-40% load for N+1 redundancy. That explains the poor input PF Randy and Gary mentioned. What are my options here - load sharing, PF correction on the input side, or just eating the penalties? The 9395s are supposed to have decent input PF but maybe not at such light loading.
The Eaton 9395 series has input PF around 0.75-0.78 at 40% load, so your numbers match what TECO is seeing. Options: 1) Load-share to run fewer units at higher loading (60-70% each), 2) Install input-side capacitor banks with harmonic filtering, or 3) Upgrade to newer UPS with better light-load input PF like the Eaton 93PM series. Option 1 is cheapest if your redundancy requirements allow it. Option 2 costs about $30-50K but pays back in 12-18 months at $4,200/month penalties.
Kevin, also check if TECO offers any power factor exemptions for critical facilities like data centers. Here in California, some utilities recognize that data center redundancy requirements can conflict with optimal power factor operation. SCE has provisions for facilities that can demonstrate the PF issues are due to required redundancy rather than poor design. Might be worth a conversation with TECO's key accounts team.