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8. Testing the Trip Unit and Circuit Breaker
8. Testing the Trip Unit and Circuit
Breaker
Testing prior to startup shall be accomplished with the
circuit breaker either in a de-energized system, or in TEST
or DISCONNECTED cassette position, or WITHDRAWN
from the cell.
N
ote:
Since time-current settings are based on desired
system coordination and protection schemes,
the protection settings, if altered during any
test sequence, should be reset to their as-found
conditions.
WARNING
Do not attempt to install, test, or perform
maintenance on equipment while it is energized.
Death or severe personal injury can result from
contact with energized equipment. De-energize the
circuit and disconnect the circuit breaker before
performing maintenance or tests.
Any tripping operation will cause disruption of service
and possible personal injury, resulting in the unnecessary
switching of connected equipment. Testing a circuit
breaker while it is in-service and carrying load current is
not recommended. Testing of a circuit breaker that results
in the tripping of the circuit breaker should be done only
with the circuit breaker in the test or disconnected cell
positions or while the circuit breaker is on a test bench.
The system will prevent a test if more than 5% of the
rated current (In) is sensed. A password is required to
prevent unauthorized use which could lead to the tripping
of the breaker. The default password is 0000.
8.1 Functional Current Testing (Remote) via USB
/ PTM
The Functional Current Testing uses the PTM software
to control testing of long delay trip, short delay trip,
instantaneous trip, and ground (earth) fault trip via the
USB communication. The Functional Current Test feature
allows for testing on any phase including neutral. The trip
unit's display is used to observe the current being injected
and the elapsed time until trip. On the PTM software,
the test mode allows the user to enter a current to be
injected, initiate the test, observe operation, and record
the results.
This is a test to verify the trip unit's internal firmware
integrity. The test current values are simulated in the trip
unit's firmware algorithm to check its integrity.
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PT 10 TrIP UnIT User ManUal Power TrIP (PT) UnITs MN013021EN January 2024 www.eaton.com
CAUTION
8.2 Testing for Ground Fault Trip Units – Primary
Injection
8.2.1 Codes and Regulations
Many local or country building codes require that any
ground fault protection system be performance tested
when first installed. Conduct tests in accordance with the
approved instructions provided with the equipment. Make
a written record of this test and make the results available
to the authority having inspection jurisdiction.
Using PTM software, you can print out a copy of the
circuit breaker's settings to keep with the testing records.
8.2.2 Test Instructions
The interconnected system must be evaluated only by
qualified personnel and in accordance with the equipment
assembler's detailed instructions.
WARNING
Electrical shock or burn injury can occur when
working on power systems. Always turn off the main
power that is supplying the circuit breaker before
conducting tests. Test out of the cell, if possible.
To avoid improper operations following apparently
correct simulated test operations, the polarity of the
neutral sensor connections (if used) must agree with the
equipment assembler's detailed instructions. Where a
question exists, consult the specifying engineer and/or
equipment assembler.
Verify the grounding points of the system using high
voltage testers and resistance bridges to ensure that
ground paths do not exist that could bypass the sensors.
Use a low voltage (0 to 24 volts), high-current, AC source
to apply a test current of 125 % of the ground pickup
setting through one phase of the circuit breaker. This
should cause the circuit breaker to trip in less than one
second and operate the alarm indicator, if one is supplied.
Reset the circuit breaker and the alarm indicator. Repeat
the test on the other two phases.
Apply the same current as described above through one
phase of the circuit breaker, returning through the neutral
sensor if a neutral sensor is used. The breaker should not
trip, and the alarm indicator, if one is supplied, should not
operate. Repeat the test on the other two phases.
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