Insulation Resistance Testing Services in Pakistan.
TransfoLine offers expert Insulation Resistance (IR) Testing using calibrated 5kV and 10kV Megger instruments to evaluate the dielectric health of power transformers, industrial 3-phase motors, generators, switchgears, and power cables. We accurately detect insulation degradation, moisture ingress, and winding faults before catastrophic short-circuits occur.
What is Insulation Resistance Testing?
Insulation resistance testing (often called Megger testing) is a non-destructive electrical diagnostic test that measures the total electrical resistance offered by the insulation of wires, transformer windings, motor coils, and busbars against high DC voltage. By measuring leakage current through the insulation material, our engineers verify dielectric strength and establish whether the equipment is safe to energize.
Polarization Index (PI) Testing
Measures resistance at 1 minute and 10 minutes (R10 / R1). A PI score above 2.0 proves that insulation is dry and free of conductive chemical contaminants, whereas values below 1.5 indicate urgent drying or repair requirements.
Dielectric Absorption Ratio (DAR)
Evaluates the ratio of resistance at 60 seconds versus 30 seconds (R60s / R30s). Ideal for quickly testing shorter cable runs and smaller equipment where 10-minute testing is not required.
Equipment We Test Across Industrial Facilities
TransfoLine provides certified on-site Megger testing across diverse industrial apparatus throughout Pakistan.
IEEE 43 Recommended Test Voltages & Minimum Values
Standard test potentials applied by our certified engineers based on operating voltage classes.
| Equipment Rated Voltage | DC Test Voltage Applied | Minimum Acceptable Resistance | Target Healthy Value |
|---|---|---|---|
| Up to 250 V (Control Circuits) | 500 V DC | > 1.0 MΩ | > 50 MΩ |
| 415 V – 1000 V (LT Equipment) | 1,000 V DC | > 2.0 MΩ | > 100 MΩ |
| 3.3 kV – 6.6 kV (MV Equipment) | 2,500 V – 5,000 V DC | > 100 MΩ | > 1,000 MΩ (1 GΩ) |
| 11 kV – 33 kV (HT Equipment) | 5,000 V – 10,000 V DC | > 500 MΩ | > 5,000 MΩ (5 GΩ) |
Insulation Testing Questions, Answered.
Technical guidance from our senior high-voltage testing engineers.
GENERAL What causes insulation resistance to drop in industrial equipment?
The primary causes of insulation breakdown in Pakistan's industrial environment are moisture absorption from humidity, carbon dust build-up in textile and steel mills, chemical contamination, thermal aging from continuous overload, and mechanical stress from vibration.
INTERPRET What is the difference between Megger test and Hipot test?
A Megger test measures the actual resistance value of insulation under DC voltage to monitor condition and aging. A High Potential (Hipot) test applies an overvoltage to verify whether the insulation can withstand severe surges without dielectric breakdown.
SAFETY Is the Megger test safe for older electrical equipment?
Yes. When conducted by qualified engineers using proper voltage step-up procedures and guard terminals, insulation testing is non-destructive and safely pinpoints weaknesses before energization.
REPORT What is included in the TransfoLine test certificate?
Your certified report includes ambient temperature correction, 30s/60s/10min resistance readings, calculated DAR and PI values, comparative benchmark graphs, and clear PASS/FAIL/RECOMMENDATION status signed by our electrical engineer.
Book an Insulation Resistance Test.
Our testing engineers deploy on-site across Pakistan within 24 hours.
Need urgent troubleshooting or routine compliance testing? Call our engineering department.