A municipal utility upgraded a 33/11 kV distribution substation and needed a complete set of indoor instrument transformers for the new switchgear: feeder, transformer and incomer bays, each with metering and protection cores.
The challenge
Delivery had to fit the substation outage window, and every bay needed a defined accuracy split: 0.2S on metering cores feeding the billing meters, 10P10 on protection cores feeding the feeder relays. Panel dimensions were fixed, so the units had to match the existing cut-outs exactly.
Our solution
We matched every unit to the panel drawings, then batch-tested the full set before shipping: ratio, polarity and dielectric tests on each unit, with test certificates issued per serial number. Crating and documentation were prepared for the scheduled outage date.
Products supplied
Cast-resin indoor current transformers (LZZBJ9 series) and indoor voltage transformers (JDZ10 series) with 100/√3 V secondaries, covering the incomer, transformer and feeder bays at 11 kV.
Outcome
All units mounted in the existing panels without modification, and the substation was re-energised on schedule. Metering accuracy was confirmed by the utility's own secondary injection tests during commissioning.