Performed annually or more often as required. Examines operating electrical systems and devices to identify connections or components operating at higher-then-normal temperatures. Can be performes with your equipment operating.

Annual test compares actual operation to published standards. Tests include pickup, time delay, target and seal-in, instantaneous trip and insulation resistance.

A. Dielectric Test - Reveals the degree of oil contamination.

B. Neutralization Number - Gauges an oil's deviation from neutral.

C. Color Number - The color of the oil is compared to ASTM standards and assigned a standard number.

D. Interfacial Tension - Measures the concentration of polar molecules in the liquid.

Involves gas chromatography using the electron capture method to quantify several of the dissolved gases in the oil.

Evaluates proper mechanical operation, freedom and adjustment of linkages, working indicating lights, insulation resistance, contact resistance, power dissipation factor (watts loss), travel test, etc.

A high-current test set produces actual fault current values to evaluate trip time and, if applicable, actual value of current required for instantaneous tripping can be determined.

A specially designed instrument measures the actual turns ratio of a transformer to determine shorted turns, verifying tap settings, etc.

Tests insulation resistance using a direct-reading megohmmeter producing a test voltage of 500 to 5000 volts D.C. - most commonly 1,000 volts.

Predicting and Preventing Trouble with Infrared Scanning

Lightning Arrester Lead Length Short