PRODUCTS > CURRENT TRANSFORMERS

Custom Current Transformers, Wound to Your Ratio

Pacific Transformer designs and builds custom current transformers wound to your exact ratio, burden, and accuracy class — wound, window, or bar-type. From revenue metering to protective relaying, from a single calibration unit to 10,000+ unit production runs.

Free engineering designs. Quotes in 24 hours. Prototypes in 48. Catalog pricing on custom work.

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Custom current transformers for metering and protection

Wound to Spec

Current Transformers, Wound to Spec

A current transformer steps a large primary current down to a safe, standardized secondary current — typically 5 A or 1 A — so meters, relays, and monitoring equipment can measure it without being connected to the primary circuit. We wind CTs from 5 A up to 5000 A primary, in metering classes (0.3 / 0.6) and protection C-classes, with the burden and frequency your system actually runs at.

Window (donut) type for a conductor you pass through, bar-type with the primary built in, or fully wound for low-current ratios — our engineers spec the right construction for free, and every unit is individually tested and ratio-verified before it ships, not batch-sampled.

Send us your specs

Typical Specifications PTC-CT

Configuration Wound, window (donut) & bar-type

Current Ratios 5 A to 5000 A primary / 5 A or 1 A secondary + custom

Accuracy Class Metering (0.3 / 0.6) & protection (C-class)

Burden 2.5 to 45 VA

Frequency 50 / 60 / 400 Hz

Order Quantity No minimums, no maximums

5000A

Max Primary Current

0.3Class

Metering Accuracy

400Hz

50 / 60 / 400 Hz

0MOQ

No Minimums, No Maximums

Applications

Where Current Transformers Are Used

Anywhere current has to be measured safely and accurately — from the revenue meter to the protective relay to the test bench.

Revenue Metering

Class 0.3 accuracy for billing-grade energy measurement at utility and submetering points.

Protective Relaying

C-class protection CTs that hold ratio through fault currents so relays trip correctly.

Power & Energy Monitoring

Feed PLC, SCADA, and building-management systems with clean, scaled current signals.

Test & Calibration

High-accuracy reference CTs for lab benches, test stands, and calibration fixtures.

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Industries Served

From NASA payloads to guitar amplifiers, Pacific Transformer's custom magnetics power some of the most demanding applications in the world. Our engineering team has deep experience across industries where compliance, performance, and reliability aren't optional — they're required.

Aerospace

Defense

Medical & Dental

Automotive & EV

Audio

Conveyance Systems

Industrial & Commercial

Power Quality & Measurement

Alternative Energy

Data Center

Utilities

FREQUENTLY ASKED QUESTIONS

Current Transformers

A current transformer (CT) produces a secondary current proportional to the current flowing in its primary conductor. It scales a large current — hundreds or thousands of amps — down to a standard 5 A or 1 A signal that meters, relays, and monitoring equipment can safely measure.

A window (donut) CT has an opening you pass the existing conductor through, making it the easiest to retrofit. A bar-type CT has the primary conductor built into the unit. A wound CT has an actual multi-turn primary winding, which is how we hit accurate ratios at lower primary currents. We recommend the construction that fits your ratio and mechanical constraints.

Metering classes (0.3 / 0.6) are specified when the CT feeds billing or energy measurement and accuracy at normal load matters most. Protection C-classes are specified when the CT feeds relays and has to stay accurate during fault currents many times rated. Tell us the application and we will spec it.

No — no minimums and no maximums. We build from a single prototype through full production runs, with free engineering and a working prototype typically in 48 hours.

Send Us Your Specs

Specs in — a quote back in 24 hours.

Tell us what you're building. A Pacific Transformer applications engineer reviews every request and responds with pricing and lead time — no forms routed to a sales queue.

24HR

Quote turnaround

Pricing and lead time within 24 hours

48HR

Prototype turnaround

A wound, tested prototype in 48 hours

Prefer to talk it through? 800-325-0501

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