FAQ
1.How do I select a current transformer of appropriate capacity for my system?
Selecting the right low-voltage current transformer requires consideration of three core factors:
First, the primary to secondary current ratio (1000A/5A); second, determining the physical window size of the device to match your busbars or cables; and finally, calculating the secondary side rated load (Burden/VA) to ensure it can drive your smart power meters or other measuring terminals without sacrificing accuracy.
2.What is the difference between a current transformer and a voltage transformer?
Both are key instrument transformers in power systems, but they have different functions.
Current transformers are connected in series in a circuit to proportionally convert large currents into standard small currents (typically 5A or 1A); while voltage transformers (VT/PT) are connected in parallel in a circuit to reduce high voltages to safe, measurable voltages. Our CT products focus on providing high-precision current conversion solutions for various switchgear applications.
3. What are the accuracy classes of current transformers? What is the difference between 0.2s and 0.5s?
The accuracy class determines the range of measurement error.
0.5s class current transformers are typically used for routine industrial current monitoring; while 0.2s class transformers offer extremely high accuracy and are specifically designed for precise metering measurements over a wide load range. If you are building a high-precision energy management system, we recommend using 0.2s class transformers to ensure data consistency.
4. How to install a split core current transformer without cutting power?
For existing distribution boxes or the renovation of old systems, cutting off the power supply is costly.
We offer high-performance split-core current transformers. Their removable core design allows engineers to clip them directly onto existing cables or busbars without disconnecting the main circuit, significantly improving installation efficiency.
5. Why must the secondary side of a current transformer never be open-circuited?
This is a crucial safety standard.
If current flows through the primary side of an instrument transformer and the secondary side is open, a dangerously high voltage will be generated in the secondary winding. This can not only break down the coil insulation but also endanger the personal safety of operators and damage the downstream protective relays. Therefore, the secondary side must be short-circuited before removing the instrument.
6.What are the effects of different magnetic core materials on the performance of current transformers?
The core material directly determines the sensitivity and linearity of the current transformer.
For standard industrial measurements, we typically use high-quality silicon steel cores, which offer excellent cost-effectiveness and stability. For zero-sequence current transformers requiring extremely high precision or to capture minute leakage currents, we use high-permeability permalloy cores. As a professional current transformer manufacturer, we can customize cores to meet your application needs.
7. What are the unique advantages of current transformers made using resin casting technology?
Compared to conventional flame-retardant molded housing instrument transformers, those using epoxy resin vacuum casting completely seal the coil and core. This structure not only provides superior electrical insulation and mechanical strength but also offers moisture, dust, and corrosion resistance, making it ideal for harsh environments such as heavy industrial workshops or complex outdoor equipment cabinets.
8.Will the harmonics caused by the frequency converter affect the accuracy of the current transformer?
Yes, variable frequency drives (VFDs) generate a large number of high-frequency harmonics during operation.
Which can cause ordinary instrument transformers to overheat or cause measurement distortion. For environments with complex power quality, we have optimized electromagnetic interference immunity during the design phase and it can be used with a power quality analyzer to ensure stable output under complex waveforms.
9. What quality tests do you conduct before shipping your products?
We implement extremely rigorous factory inspection procedures.
Every current transformer must undergo current transformer calibration and testing before leaving the factory, including polarity testing, power frequency withstand voltage testing, and full-load accuracy verification. We ensure that all products leaving the factory fully comply with international electrical standards such as IEC 61869.
10. Do you support customized and bulk purchases of current transformers?
Of course we support you.
As an experienced supplier of custom CT transformers, our engineering team can provide OEM/ODM services for special sizes, ratios, and non-standard mounting brackets. For wholesale current transformer orders, we have ample production capacity to ensure competitive prices and stable delivery times.