6. Frequently Asked Questions
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The ZMCT102W is rated for 0–20 A on the primary. It uses a 2000:1 turns ratio, meaning 2000 turns on the secondary for every turn of the primary path.
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It delivers 2.5 mA on the secondary when 5 A flows in the primary (with a 100 Ω burden). At 20 A primary, the output would scale to 10 mA (assuming linearity).
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It’s specified as Accuracy Class 0.2 (IEC standard). Linearity error is ≤0.2% between 5% and 120% of rated current. Permissible error is ±0.2% at 1 A (with specified burden). In practice, small currents (<5% of 20 A) have higher relative error.
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It’s tested for 4500 V isolation (turns insulation), meaning it can safely withstand high voltage between primary and secondary. This makes it safe for use in mains-voltage systems when properly installed.
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ZMCT102W is designed for PCB mounting. It has output leads or pins that go through the PCB for soldering. The primary conductor is simply the core window (the board trace or lead-through carries the primary current). Ensure pins are soldered and the transformer is placed to avoid magnetic coupling with other components.
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No. This is an AC current transformer. It requires AC excitation (50/60 Hz). Any DC in the primary would magnetize and saturate the ferrite core, producing no valid secondary output. It measures only AC components.
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Use a precision resistor on the secondary (e.g. 100 Ω) to develop a measurable voltage. For example, at 5 A primary the 2.5 mA output across 100 Ω yields 250 mV. The transformer’s specs assume a 100 Ω burden (as noted in datasheet conditions).
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It’s optimized for power-line AC (50/60 Hz). It will work on nearby frequencies but accuracy is not guaranteed outside the specified band. It is not designed for high-frequency signals (e.g. > kHz).
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The ZMCT series includes other models (e.g. ZMCT102 with PCB pins, ZMCT102W with leads). Other CTs or Hall sensors may be used, but ZMCT102W is favored for its compactness and precision in PCB applications.