The MSJS‑EA Dielectric Loss Tester is a professional instrument for measuring tan‑delta (dielectric loss factor) and capacitance of high‑voltage insulation components. It is widely applied to insulation performance evaluation for transformers, instrument transformers, bushings, power capacitors and CVT units.
Equipped with variable‑frequency power supply and single‑chip digital processing technology, the device provides outstanding 50 Hz power‑frequency interference rejection, making it highly suitable for on‑site tests inside substations with heavy electromagnetic interference.

Main Features

• Advanced Fourier digital filtering and variable‑frequency anti‑interference algorithm, maintaining accurate readings even under 200% field interference.
• Large full‑touch screen for intuitive and convenient operation.
• Built‑in real‑time clock and large‑capacity onboard storage for test records; data can be exported via USB flash drive. Supporting upper‑computer management software and RS232 communication port, multiple units can be integrated into a mobile high‑voltage test vehicle system.
• All‑in‑one main unit with integrated standard reference capacitor and high‑voltage source, also supporting oil dielectric loss measurement.
• Multiple test modes: UST, GST, GST with low‑voltage shielding and CVT self‑excitation mode. The CVT self‑excitation function automatically calculates C1, C2 and total capacitance & tan‑delta values. It also supports secondary AC withstand‑voltage test for CT / PT.
• Compatible with external 40‑70 Hz high‑voltage sources, such as power‑frequency or series‑resonance test sets.
• Integrated thermal printer for on‑site report output.
• Multi‑layer hardware & software safety protection against over‑current, electric shock and grounding‑fault risks. High‑voltage output will not activate without reliable ground connection.

Technical Specifications

• Measurement Accuracy
  Cx: ±(reading ×1% + 1 pF)
  tgδ: ±(reading ×1% + 0.00040)
• Capacitance measuring range:
  Built‑in HV: 3 pF‑60000 pF
  External HV: 3 pF‑1.5 μF
• tgδ resolution: 0.001%
• Test current: 10 μA‑5 A
• Built‑in high‑voltage output: 0.5‑10 kV, max. output current 200 mA （12KV optional）
• Test frequency: single‑frequency 40‑70 Hz; dual‑frequency 45 Hz / 55 Hz variable‑frequency mode
• Single measurement cycle: approx. 40 seconds
• Power supply: AC 180‑270 V
• Operating temperature: ‑10 ℃ ~ 50 ℃
• Net weight: 28 kg
• Overall dimension: 500 × 377 × 330 mm

Application Scope

This tester is designed for on‑site insulation diagnosis of power‑grid equipment. The dual‑frequency 45 Hz / 55 Hz measurement effectively filters out 50 Hz ambient interference and calculates equivalent 50 Hz tan‑delta values.
It is the mainstream field‑testing solution for routine maintenance, overhaul inspection and fault diagnosis of high‑voltage power apparatus

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