Looking for high current testing standard for breakers

[Larry5443]

Does anyone have a standard for high current testing breakers ,I have not seen anything from NETA

[SecondGen]

what kind of standard are you looking for? I have some manufacturers field testing manuals that cover primary injection testing.

[Larry5443]

Long time is %300 or %600. There is nothing for short time and instantaneous is 10 times breaker rating ground fault is questionable

[SecondGen]

I was able to find a section from a Square D Field Maintenance Guide for electronic trip circuit breakers that covers performance testing. Looks like this might be what you are looking for, it has procedures for Long Time, Short Time, Instantaneous and Ground Fault as well as Insulation Resistance and Contact Resistance tests. See the document attached to this post. Hope this helps.

[SecondGen]

Looks like long time is 300%, short time delay and ground fault are 150%, according to Square D. For instantaneous start at 70% of expected trip value and apply 10-cycle pulses as you raise current.

[Larry5443]

Are they saying that %150 for short time and ground fault is what calculation is it % 150 of what

[SecondGen]

150% of the determined pickup value. All dependent on your trip settings at time of test.


Are they saying that %150 for short time and ground fault is what calculation is it % 150 of what

[Larry5443]

Can you explain with a formula please

[SecondGen]

Here is a quick example: If you had a 1000A circuit breaker with a short time pickup of 3X it should trip on short time around 3000A. You would first verify that by turning off I2t (if applicable) and ramp up current starting from about 2500A, the breaker should trip around 3000A. Next, turn I2t back on (if applicable) and preset your current to 150% of the pickup value (in this case: 3000A x 1.5 = 4500A). Initate current at that value and the breaker should trip within its specified time.

Give that PDF a read, it is all explained in there stp by step.

[Larry5443]

I understand what you are saying ,Iam asking is there anything that is written as far as a standard from Neta or anyone else in the testing organization .

[SecondGen]

There isn't anything I know of that comes directly from NETA covering circuit breaker primary injection testing procedures. :confused: NETA specs usually tell you to consult manufacturers recommendations for specific procedures.

[CoDylan]

NETA Tests for Low-Voltage Power Circuit Breaker (LSIG):
1. Determine long-time pickup and delay by primary current injection.
2. Determine short-time pickup and delay by primary current injection.
3. Determine ground-fault pickup and delay by primary current injection.
4. Determine instantaneous pickup current by primary current injection.

NETA Test Results for Low-Voltage Power Circuit Breaker (LSIG):
1. Long-time pickup values should be as specified, and the trip characteristic shall not exceed manufacturer’s published time-current characteristic tolerance band.
2. Short-time pickup values should be as specified, and the trip characteristic should not exceed manufacturer’s published time-current tolerance band.
3. Ground fault pickup values should be as specified, and the trip characteristic should not exceed manufacturer’s published time-current tolerance band.
4. Instantaneous pickup values should be within the tolerances of manufacturer’s published data.

The reason why there is not a test percentage within the NETA specifications is that the expectation is the unit will function as specified at any point of the time-current curve or manufacturer's tolerance, not just at one specific value. Although it is common industry practice to test long time at 300% of pickup and short time and ground fault at 150% of pickup. Instantaneous is per the curve tolerance.

[JohnRaz]

TABLE 100.7 deals with Inverse Time Trip Tests
at 300% of Rated Continuous Current Molded-Case Circuit Breakers.
Maximum trip times

[JohnRaz]

TABLE 100.8 deals with Instantaneous Trip Tolerances
for Field Testing of Circuit Breakers

[luhanson1]

NFPA-70B explains low voltage breaker testing a little clearer than NETA.