The wire itself is usually copper or aluminum, which is known to be a good conductor of the electric current that powers your equipment. The insulation must be just the opposite from a conductor: it should resist current and keep the current in its path along the conductor.
When an electrical system and equipment are new, the electrical insulation should be in top notch shape. As time goes on, insulation is subject to many effects which can cause it to fail – mechanical damage, vibration, excessive heat or cold, dirt, oil, corrosive vapors, moisture from processes, or just the humidity on a muggy day.
To test cable insulation consider the Megger MIT525 5-kV Insulation Resistance Tester.
Capable of conducting various tests on insulators found in cables, transformers and motors, the Megger MIT525 is rated CATIV 600 volts on all terminals and an Ingress Protection 65.
The Megger MIT525 can also conduct automatic Step Voltage, Ramp and Dielectric Discharge tests, and features a real time clock and PC connectivity through USB and RS232 ports. The PC connectivity allows advanced results analysis using the PowerDB Lite software.
• Analog and Digital display
• Operation through batteries or through AC mains
• Variable voltage from 50 Volts to 1 kiloVolts at 10 Volts increments
• Variable voltage from 1 kiloVolts to 5 kiloVolts at 25 volts increments
• Measurement of voltage, capacitance, time constant and leakage current
• Automatic Insulation Resistance, Polarization Index, Ramp, Step Voltage, Dielectric Discharge and Dielectric Absorption Ratio testing
• Built-in timer control and display
• 3 milliampere test current
• Measurement of resistance from 10 kΩ to 10 TΩ
• USB and RS232 ports
• Real time clock
• Alarm limit mode
• 3 milliampere noise rejection
• 2 percent error guarding 500 kΩ leakage with a 100 MΩ