Description
Product Introduction
The GE CT12AUF2K0MA current transformer transforms 10 kV to 12 kV primary medium-voltage currents down to standard 5 A secondary signals for switchgear metering and relay protection. Designed for indoor switchgear assemblies such as KYN28 cabinets, this unit provides electrical isolation between high-voltage busbars and secondary instruments. Bottom line — it works.
Vacuum-cast epoxy resin encases both measurement and protection cores into a single monolithic body, preventing internal partial discharge below 10 pC. Operating across -25 to +55 °C, the dual-winding system maintains 0.2S class precision for utility billing while delivering 10P protection response during short-circuit faults. Honestly, integrating billing-grade metering with anti-saturation fault protection into one block is actually clever for saving switchgear compartment space.
Installation & Configuration Guide
Phase 1 — Pre-Installation (est. 10 min)
- Lock out and tag out the main feeder circuit breaker feeding the switchgear bay.
- Ground all primary phase busbars and wait 5 minutes for discharge.
- Bring a 2,500 V megohmmeter, a torque wrench, a Fluke 115 multimeter, and protective footwear.
- Export protection relay settings and photograph terminal wiring labels before touching cables.
Phase 2 — Removal (est. 5 min)
- Disconnect secondary terminal wires from terminal blocks $1S1$, $1S2$, $2S1$, and $2S2$.
- Remove primary busbar mounting bolts connecting the transformer primary terminals.
- Support the physical weight of the transformer body using a lift harness.
- Unbolt chassis base mounting hardware and extract the transformer straight outward from the compartment.
Phase 3 — Installation (est. 10 min)
- Put on an anti-static wrist strap before touching secondary electronic interface equipment.
- Inspect the nameplate to confirm the part number reads GE CT12AUF2K0MA.
- Position the transformer onto cabinet base rails and tighten mounting bolts to 25 N·m.
- Connect primary copper busbars to high-voltage terminals using M12 hardware torqued to 45 N·m.
- Wire secondary terminals $1S1/1S2$ (metering) and $2S1/2S2$ (protection) securely, ensuring secondary circuits are never open-circuited under load.
Phase 4 — Power-On & Testing (est. 15 min)
- Measure primary-to-secondary and primary-to-ground insulation resistance using a 2,500 V megohmmeter.
- Inject a low-voltage test current into the primary winding to verify secondary current ratio and polarity ($P1-P2$ vs $S1-S2$).
- Remove safety grounding jumpers and close the bay enclosure doors.
- Energize the 12 kV incoming busbar.
- Monitor secondary current readings on downstream digital meters for 30 minutes to confirm continuous signal integrity.
Quality Verification SOP
In field deployments of medium-voltage switchgear, rigorous component validation prevents catastrophic flashovers and revenue metering errors. Every GE CT12AUF2K0MA unit undergoes strict physical and electrical verification prior to dispatch:
- Incoming Inspection: We verify OEM packing lists, customs documentation, and serial tags. Technicians inspect the epoxy resin body under bright light for micro-cracks, surface voiding, terminal thread damage, or surface contamination.
- Live Functional Test: Placing the unit on a current injection test stand, we inject primary currents up to rated levels. We verify ratio errors across 1% to 120% nominal current and log excitation curves for the 10P protection core over a continuous 24-hour heat-run test. A formal Test Report accompanies every unit.
- Electrical Tests: We test primary-to-ground and primary-to-secondary insulation using a 2,500 V megohmmeter (confirming >1,000 MΩ). Power-frequency withstand capability is verified up to 42 kV for 1 minute.
- Ratio & Polarity Verification: Secondary polarity is verified through pulse testing, and terminal designation markings are photographed for quality records.
- Final QC & Packaging: After technician sign-off, the unit is wrapped in heavy moisture-proof plastic film, cushioned with high-density shock foam inside a reinforced wooden crate, and sealed with a dated QC Passed badge.
(Note: Full test photos and raw injection test logs are available on request. All units are confirmed functional after completing all verification steps listed above.)
