Testing Procedures

Standard Production Test Procedures

1. Low Voltage Air Circuit Breakers (600 Volt and below)
(Applicable Production Test Procedures: 2,4,5,6,7,8,9)

2. Medium/High Voltage Air Circuit Breakers (600 Volt and above)
(Applicable Production Test Procedures: 1,2,3,4,5,6,7)

3. Low Voltage Switchgear
(Applicable Production Test Procedures: 2,4,5,6,7)

4. Medium/High Voltage Switchgear
(Applicable Production Test Procedures: 1,2,3,4,5,6,7,9)

Standard Production Test Procedures
Table of Contents

AC High Potential Test

Digital Low Resistance Ohmmeter

DC High Potential Test

Electrical Operation Test

Mechanical Operation Test


Multi-Voltage Tester

Overload Coordination Tester

Three Phase Primary Injection Test

Optional Tests

AC High Potential Test Set

This test set generates AC test voltages from 0-120,000 volts at currents between 0-5MA.

The test set is used to evaluate insulating materials, resistive and reactive properties.

The results are recorded as leakage current which is converted to resistance.

The resulting resistance can be used together with the DC hi-pot test readings to determine the AC resistance component for insulation evaluation.

Digital Low Resistance Ohmmeter (Kelvin Bridge)

The DLRO is a direct reading 100 Amp, 4 wire digital ohmmeter.

The DLRO is used to measure the DC resistance of contacts in a conducting path.

The DLRO is operated by applying a DC current through the desired conducting path.

The readings (DC micro-ohms) indicate the resistance at the contacts. This data is used to determine the amount of heating that can occur at the contacts as a result of the current flow through this connection.
DC High Potential Test

The test set generates DC voltages from 0-80,000 volts at currents between 0-10MA.

The testing potential is applied across the insulating medium in question, (bushing, standoff, barrier, buss bar, open air gaps, etc) raised to published voltage stress standards and maintained for one (1) minute.

The results are recorded as leakage current which is converted to resistance (typically megohms).

The resulting resistance readings are used in determining the insulation integrity in medium voltage air circuit breakers.

Electrical Operation Test

During this test the technician insures that all electrical functions of a circuit beaker or switchgear section(s) are operating properly and adhere to all customer and manufacturer’s specifications.

Such tests include:
Close and trip coil operate within published ranges

Control relay sequence and timing
Auxiliary contact conductance
Proper charging motor operation
Meggar test insulation/components

Mechanical Operation Test

During this test the technician insures that all mechanical functions of a circuit breaker or switchgear section(s) are operating properly and adhere to all customer and manufacturer’s specifications.

Such tests include:
Prop clearances

Contact wipe
Gap measurements
Bolt torque test
Elevating mechanism operation
Interlock coordination
Complete circuit breaker operation


The megohmmeter (meggar) is a high resistance ohmmeter used to measure insulating materials at test voltages between 0 and 5000 VDC.
The meggar is operated in the same fashion as an ohmmeter in that the measuring leads are applied to the sample and results are recorded.

The recorded readings are direct readings in megohms and are used to determine the integrity of the insulation in low voltage (600 Volt) air circuit breakers or control wiring insulation.

Multi-Voltage Test Set

The multi-voltage test set is an adjustable voltage source capable of generating AC/DC, single and three phase voltages between 0-600 volts.

The above test set allows operation and control testing of circuit breaker control circuits and switchgear control circuits, over the published ranges

Overload Coordination Test Set

This test set is a low voltage, high current test device used to test the performance of electromechanical overloads and solid state trip devices in low voltage air circuit breakers. The test set is rated for operation at 20,000 amps continuous and 100,000 amps instantaneous.

The air circuit breaker is connected to the test set directly by use of the primary disconnects and current is raised to the proper levels to test all circuit breaker functions and characteristics that will ultimately trip the circuit breaker. All characteristics (long time, short time and instantaneous) are verified to fall within original manufacturer’s published curves.

The above tests the ability of the air circuit breaker to sustain high current, hot spots on the contacts and verifies that the overloads or solid state package operate properly within a given range of times.

Three Phase Primary Injection Test

This test is designed to test the high current circuits in switchgear. Current transformer ratios, meter circuits and protective relay circuits are verified for proper operation by this test.

The current ranges are typically 50-5,000 AC amperes, depending on the ratings of the switchgear.

The test set is connected to the three primary conducting phases in the switchgear and the current levels are raised and monitored to check all applicable instruments in the primary current path.

The results will confirm and verify that all relays and metering systems are performing within the published times.

Optional Tests
Speed and Motion Test

A mechanical transducer is coupled externally to the operating rod of the air circuit breaker, which in turn provides the circuit breaker motion analyzer with electrical signals corresponding to the travel and velocity of the operating rod. A set of cables connect the motion analyzer to the circuit breaker contacts and the control circuit. Three phases can be monitored simultaneously.

The results are interpreted against published time standards which measures the electrical/mechanical performance of the circuit breaker.
Power Factor

This test set generates AC voltages from 0-12,000 Volts and is used to measure the dielectric loss of insulating materials.

The capacitance of the specimen is being measured, from which the power factor can be computed.

This value can be used to chart the deterioration of the insulating specimen over time.