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What Is LMK7 Series Low Voltage Current Transformer?
The LMK7 series low voltage current transformer is a three-phase current transformer specially designed for collecting current signals in low-voltage AC circuits. Its design strictly follows the threading dimensions of the CM1 molded case circuit breaker standard, ensuring seamless integration with common switchgear. This current transformer features a wide measurement range, with a rated primary current up to 1000A and a rated secondary current range from 20mA to 5A. It is manufactured using an excellent and advanced production process and complies with IEC 61869. The LMK7 series adopts a core piercing structure with flame-retardant epoxy resin casting, offering good stability, high linearity, high sensitivity, and strong anti-electromagnetic interference capability.
Working Conditions of the LMK7 Series Low Voltage Current Transformer
- Installation site: Indoor (e.g., switchgear, fire monitoring panels)
- Applicable conductors: Copper wires and cables
- Primary current range: Up to 1000A
- Secondary current range: 20mA ~ 5A
- Standard compliance: IEC 61869
- Housing material: Flame-retardant epoxy resin casting
Why Choose ZHIMING's LMK7 Series Low Voltage Current Transformer?
Designed Specifically
This current transformer is strictly dimensioned according to the CM1 circuit breaker threading size, ensuring a perfect fit without modification. This design reduces installation complexity and saves space inside the panel.
Wide Measurement Range
With a primary current range up to 1000A and secondary output options from 20mA to 5A, this current transformer accommodates both traditional 5A metering and low-power (mA) monitoring applications. This flexibility makes it suitable for various protection and measurement devices.
Excellent Material and Construction
The current transformer uses high magnetic permeability nickel steel or nanocrystalline cores, which provide excellent linearity and high sensitivity even at low currents. The flame-retardant epoxy resin casting ensures good stability, mechanical strength, and fire safety.
Strong Anti-Electromagnetic Interference
Thanks to its outstanding balance characteristics and design, this current transformer offers strong immunity to external electromagnetic interference, ensuring accurate signal transmission in electrically noisy environments such as industrial switchgear and relay panels.
Versatile Application Coverage
The LMK7 series current transformer is ideal for a wide range of applications including electrical fire monitoring, current and voltage sensor equipment, fire equipment power modules, fire leakage systems, small current grounding systems, electromagnetic relay protection, and microcomputer protection.
SSS
What is the primary current range of the LMK7 series low voltage current transformer?
The rated primary current range goes up to 1000A. For specific ratio options (e.g., 200A/5A, 400A/20mA, etc.), please refer to the detailed ordering code or consult ZHIMING.
Can this current transformer be used with cables instead of busbars?
Yes. The core piercing structure allows both copper wires and cables to pass directly through the window. It is designed for easy installation without requiring busbar fixing.
What makes this low voltage current transformer suitable for electrical fire monitoring systems?
The LMK7 series offers high sensitivity (thanks to nanocrystalline or nickel steel cores) and a wide secondary output range down to 20mA, which is ideal for detecting small leakage or fault currents. Its flame-retardant epoxy casing also meets fire safety requirements.
Does this low voltage current transformer comply with any international standard?
Yes, the LMK7 series current transformer is designed and manufactured in accordance with IEC 61869, the international standard for instrument transformers.
How do I select the correct LMK7 low voltage current transformer for my application?
When selecting, you need to determine your required primary current (up to 1000A), desired secondary current (e.g., 5A for traditional meters or 20mA for sensors), and the conductor size (to ensure it fits through the core piercing window). Additionally, confirm that your application matches one of the listed uses such as fire monitoring, relay protection, or microcomputer protection.








