W-C-375E
TABLE XV. Current interrupting rating: RMS symmetrical amperes applicable to circuit breakers rated for high available fault current circuits.
7,500 1/ |
25,000 |
65,000 |
10,000 1/ |
30,000 |
85,000 |
14,000 |
35,000 |
100,000 |
18,000 |
42,000 |
125,000 |
22,000 |
50,000 |
150,000 |
200,000 |
1/ Applicable only to circuit breakers having continuous- current ratings of 100 amperes or less (frame size) and voltage ratings of 250 volts or less.
4.7.12 250 percent calibration at 25°C ±3°C (see 3.15). Each pole of the circuit breaker shall be subjected to the first test specified in 4.7.2, except the test current shall be 250 percent of rated current. Following the test, circuit breakers shall be subjected to the dielectric withstanding voltage test specified in 4.7.9.2.
4.7.13 Crossover (current limiters or fuses (see 3.16). Circuit breakers shall be prepared for test in accordance
with 4.7.11 (except cotton and cloth indicators shall be used (see table IV and VIII), and subjected to an "O" operation at a current level slightly above the crossover point. Following the test, limiters or fuses shall be visually examined,
cotton and cheesecloth shall be examined for evidence of burning and the circuit breaker enclosure shall be
examined for evidence of damage.
4.7.14 Crossover (dummy fuses (see 3.17). With dummy fuses installed, the circuit breaker shall be prepared for test in accordance with 4.7.11. Circuit breakers shall be subjected to one "O" and one "CO" operation at a current equal to the crossover value. Following the test, circuit breakers shall be checked for damage to the circuit breaker case, ejection of wire from the wire connector or burn off of leads, failure of a pole to trip, burned out shunts, bi- metals or heaters, mechanical failures which do not permit relatching or reclosing of the circuit breaker or other similar failures.
4.7.15 Maximum interrupting capacity (see 3.18). Circuit breakers shall be prepared for test in accordance with
4.7.11, except cotton shall be placed directly over openings in the current limiter area and the power factor of the test circuit shall be not higher than .20. Test shall be conducted on one half of the current limiters in the "as received" condition and the other half shall be conditioned at 90°C for 24 hours then subjected to 95 ±5 percent relative humidity at 20°C - 25°C for 5 days. Conditioned samples shall be tested no later than 1 hour after removal from the
conditioned environment. One "O" operation (or as specified, see 4.7.15 (a) and (b)) and one "CO" operation shall be
performed in a circuit of rated interrupting capacity.
a. During the "O" operation, a full current off-set condition is to be present in one phase upon closing the test circuit. It is the intent to initiate limiter or fuse arcing within 30 electrical degrees prior to maximum voltage in that phase. If such arcing initiates prior to maximum voltage in that phase. If such arcing initiates prior to maximum voltage, a repeat test is to be made in which closing is delayed in order to obtain the desired condition.
b. If the closing angle in item (a) is zero degrees and if arcing, within the limiter or fuse, commenced after 90 degrees on the voltage wave, the sample is to be subjected to a test in which closing occurs at maximum voltage (no current off-set). Individual poles may be used for such testing in order to avoid destroying current limiters or fuses unnecessarily.
Then an "O" operation is to be made where closure is at a point on the voltage wave 45 degrees after a voltage zero.
Following the test, the circuit breaker case and leads and the limiters or fuses shall be examined.
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