HZ-109S Primary Current Injection Tester: Fast, Accurate CT Ratio Testing

Why field engineers pick it up first

Instead of guessing, you get four readings at once on the LCD: primary current, secondary current, CT turns ratio, and the actuation (trip) time captured by the built-in stopwatch. Doing a CT ratio test used to mean juggling separate meters. Here it is one screen, one glance.

The heart of the unit is an ARM chip controlling the output paired with a high-capacity toroidal transformer. That combination is what lets a case this small push serious current. Output runs up to AC 1000A at 5V, or 500A at 10V, from a standard 220V·25A, 50Hz supply — plenty for CT turns ratio checks, polarity confirmation, and Contact Resistance Tests on switchgear and breakers.

Specs that actually matter on site

• Primary current range: 0–1100A, resolution 0.1A
• Secondary current range: 0–6A, resolution 0.001A
• Stopwatch timing: 0.0001–999.99s, ±5 significant figures
• Accuracy: TRUE RMS ±0.5%
• Duplicate protection (electronic overload + software) so a wiring mistake won't cook the unit
• Works from -10 to 40℃, relative humidity under 80%

At 430×260×260 mm and only 28 kg, with an aluminum alloy case and PC panel, it travels well. One technician can carry it into a bay, hook up the high-current leads, and start injecting.

Where it earns its keep

Anyone commissioning CTs, verifying protective relays, or troubleshooting wiring and polarity in a power system will find the HZ-109S primary current injection tester a reliable daily driver. Because Primary Injection is the only method that proves the entire circuit — CT, wiring, relay, and breaker — together, this is the tool you reach for when a "push-to-test" simply isn't enough.

Need a compact primary Current Injection test set that reads ratio and trip time in one shot? The HZ-109Sprimary current injection tester is ready to ship — reach out for pricing and a full datasheet.

FAQ:

What is a primary current injection tester used for? It injects high current directly into the primary side of a current transformer or protection device, so you can verify CT turns ratio, polarity, contact resistance, and relay trip time under real operating conditions — a full-path check that secondary injection can't provide.

How much current can the HZ-109S output? Up to AC 1000A at 5V, or 500A at 10V, from a standard 220V·25A, 50Hz supply, with a primary current range of 0–1100A.

How do you calculate CT ratio with it? Divide the primary current by the secondary current. The HZ-109S primary current injection tester shows primary current, secondary current, and the calculated turns ratio on one LCD screen at the same time.

Is primary injection better than secondary injection? For proving the entire protection chain — CT, wiring, relay, and breaker together — yes. Primary injection tests the system as it will actually behave during a fault; secondary injection only checks relay logic.

Is the HZ-109S primary current injection tester portable? Yes. At 430×260×260 mm and 28 kg, with an aluminum alloy case, one technician can carry and operate it on site.