What is Current Transformer Tester?

In the intricate landscape of electrical systems, the current transformer (CT) plays a pivotal role in transforming high currents into manageable levels for measurement and protection. Ensuring the accuracy and reliability of CTs is crucial for the proper functioning of power systems. This blog post aims to demystify the current transformer tester, shedding light on its purpose and functionality in the realm of electrical testing.

Understanding the Current Transformer Tester

Current and voltage transformer tester is also known as transformer tester, transformer tester, transformer characteristics tester, transformer characteristics tester, automatic transformer tester, automatic transformer tester, automatic transformer characteristics tester, automatic transformer characteristics tester, volt-ampere characteristics tester, volt-ampere characteristics tester, CT tester, PT tester, etc. etc. Current and voltage transformer tester is a multifunctional field test instrument specially designed for testing transformer: Volt-ampere characteristic, ratio, polarity, angular difference, ratio difference, demagnetisation, error curve, voltage withstand test and secondary side circuit check. Without the use of external standard transformers, the simulation software can be used to measure the angular difference and specific difference of the transformer; only need to set the test voltage/current value during the experiment, the device can automatically increase the voltage/current, and the transformer's volt-ampere characteristic curve or ratio, polarity, and other experimental results will be quickly displayed to support the preservation of the data and on-site printing, which not only eliminates the need to manually regulate the voltage, manual recording, tracing curves and other cumbersome labour, but also can be connected to a laptop computer through the USB interface. It can also be used on-line with laptop or upload data through USB interface. Simple and convenient operation, improve work efficiency, is a cost-effective high-tech products.

How does Current Transformer Tester Work?

When the current transformer tester supplies electricity, the magnitude of the current changes greatly, ranging from a few amperes to tens of thousands of amperes. In order to facilitate accurate measurements in meters and dashboards, they must be converted into more uniform currents.
Most analog current digital display instruments are ampere-level, so the secondary currents of current transformer testers are mostly ampere-level (such as 5A, etc.), and the data signals sampled by electronic computers are generally mah level (0-9V , 4-50mA, etc.). Therefore, a small current transformer tester (secondary current level is mah) is selected as a bridge between the current transformer tester and the computer sampling signal to perform secondary conversion of current.

The current transformer tester consists of a primary electromagnetic coil, a secondary electromagnetic coil, an iron core, an insulation layer support point, and a group outlet terminal. The core of the current transformer tester is made of laminated ferrite cores. The primary electromagnetic coil is connected in series with the main power circuit. According to the measured current I1, alternating magnetic flux is caused in the iron core, causing the two secondary electromagnetic coils to magnetically induce a relative secondary current I2 (its rated voltage is 5A). If the loss of the excitation regulator is ignored, then I1n1=I2n2, where n1 and n2 are the number of coil turns of the primary and secondary electromagnetic coils respectively. The transformation ratio of the current transformer tester is K=I1/I2=n2/n1. Since the primary electromagnetic coil of the current transformer tester is connected to the main power circuit, the primary electromagnetic coil must be grounded with an insulating material consistent with the operating voltage of the primary line to ensure the safety of the secondary circuit and personal safety. The secondary circuit is composed of the secondary electromagnetic coil of the current transformer tester, the instrument panel and the current electromagnetic coil of the automobile relay connected in series. Current transformer testers can be roughly divided into two categories, current transformer testers used for accurate measurement and current transformer testers used for repair.

Advantage

• Few wiring terminals, simple wiring method, convenient for users to use.
• The output voltage of the single-machine volt-ampere characteristic test is 0-1000V and the current is 0-15A; the maximum output current of the single-machine transformation ratio test is 0-600A.
• Fully automatic voltage boosting, current boosting, volt-ampere characteristic curve drawing, and transformation ratio calculation calculation, eliminating the tedious labor of manual voltage adjustment, manual recording, curve drawing, etc., and improving work efficiency.
• It is possible to simulate and test the angle difference and ratio difference of the transformer without the need for external standard transformers and voltage/current sources.
• Can test CT/PT volt-ampere characteristics, transformation ratio, polarity, angle difference, ratio difference, 5%, 10% error curve, secondary side loop, secondary AC withstand voltage and demagnetization and other experiments.
• Large-screen Chinese LCD display, intuitive and convenient.
• Comes with a micro-fast printer that can print curves and test data on-site.
• Using imported photoelectric rotary encoder, the operation is simple and convenient.
• Large-capacity memory can save 1,000 sets of test data and will not be lost when power is lost.
• USB communication interface, which can be connected to a laptop for testing.
• Small size, light weight, convenient for flow testing.

The Purpose of a Current Transformer Tester

A current transformer tester is a specialized device crafted for the purpose of evaluating the health and functionality of current transformers. Its primary objectives include:

• Accuracy Verification: Confirming that the CT accurately transforms current from the primary to the secondary side.
• Polarity Assessment: Verifying that the direction of current flow aligns with the marked polarity of the CT. Correct polarity is crucial for accurate measurements in power systems.
• Insulation Integrity Check: Assessing the insulation resistance between the primary and secondary windings to ensure the CT's longevity and reliability.
• Ratio Confirmation: Checking that the transformation ratio of the CT complies with manufacturer specifications.

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