Instantaneous Trip Tolerances for Field Testing of Circuit Breakers
Tolerances of Manufacturer's Published Trip Range | |||
---|---|---|---|
Circuit Breaker Type | Tolerance of Settings | High Side | Low Side |
Electronic Trip Unit (1) | +30% / -30% | ---- | ---- |
Adjustable (1) | +40% / -30% | ---- | ---- |
Nonadjustable (2) | ---- | +25% | -25% |
Notes:
- Tolerances are based on variations from the nominal settings.
- Tolerances are based on variations from the manufacturer's published trip band (i.e., -25% below the low side of the band; +25% above the high side of the band).
References: NEMA publication AB4, Table 4. ANSI/NETA-ATS 2013 Table 100.8.
Inverse Time Trip Test at 300% of Rated Continuous Current of Circuit Breakers Molded-Case Circuit Breakers
Range of Rated Continuous Current (Amperes) | Maximum Trip Time in Seconds For Each Maximum Frame Rating (1) | |
---|---|---|
≤ 250V | 251 - 600V | |
0-30 | 50 | 70 |
31-50 | 80 | 100 |
51-100 | 140 | 160 |
101-150 | 200 | 250 |
151-225 | 230 | 275 |
226-400 | 300 | 350 |
401-600 | ---- | 450 |
601-800 | ---- | 500 |
801-1000 | ---- | 600 |
1001-1200 | ---- | 700 |
1201-1600 | ---- | 775 |
1601-2000 | ---- | 800 |
2001-2500 | ---- | 850 |
2501-5000 | ---- | 900 |
6000 | ---- | 1000 |
Notes
- Trip times may be substantially longer for integrally-fused circuit breakers if tested with the fuses replaced by solid links (shorting bars).
References: NEMA Standard AB 4-1996: Guidelines for Inspection and Preventive Maintenance of Molded-Case Circuit Breakers Used in Commercial and Industrial Applications, Table 5-3. ANSI/NETA ATS-2013 Table 100.7