The document discusses synthetic testing of circuit breakers. It describes a method where an auxiliary breaker and test breaker are closed, allowing current to flow through the test breaker. When the test breaker begins to operate, a trigger gap then closes, introducing a higher frequency current to assist in clearing the arc. The generator current is disconnected precisely at zero, leaving only the higher frequency current, and applying full test voltage at the exact moment of breaking to evaluate the circuit breaker's performance.

1. TESTING OF ISOLATORS &
CIRCUIT BREAKERS
K. Karthikeyan,
Associate Professor / EEE,
Ramco Institute of Technology.

2. DIRECT TESTING IN SHORT CIRCUIT
TEST LABORATORIES
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3. SYNTHETIC TESTING OF CIRCUIT
BREAKERS
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4. SYNTHETIC TESTING OF CIRCUIT
BREAKERS
 With the auxiliary breaker (3) and the test breaker (T)
closed, the closing of the making switch (1) causes the
current to flow in the test circuit breaker.
 At some instant say to, the test circuit breaker (T) begins to
operate and the master circuit breaker (T) becomes ready
to clear the generator circuit.
 At some times t1, just before the zero of the generator
current, the trigger gap (6) closes and the higher frequency
current from the discharging capacitor Cv also flows
through the arc.
 At time t2, when the generator current is zero, the circuit
breaker (1) clears that circuit, leaving only the current from
Cv which has the required rate of change of current at its
zero flowing in the test circuit breaker.
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5. SYNTHETIC TESTING OF CIRCUIT
BREAKERS
 At the zero of this current, full test voltage will be
available.
 It is important to see that the high-current source is
disconnected and a high-voltage source applied with
absolute precision (by means of an auxiliary circuit
breaker) at the instant of circuit breaking.
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6. THANK YOU
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