Testing Provisions; Conducting Tests - Eaton Digitrip RMS 910 Instruction Leaflet

Instruction Leaflet I. L. 29-889B
Effective June 2011

4.3 Testing Provisions

As illustrated in Figures 1 and 20, an integral test panel is provided
to test the Digitrip RMS 910 Trip Unit .
While the Integral Test Panel does enable one to check the perfor-
mance of many parts of the trip system, including:
Microprocessor Functions;
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Trip Release;
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Trip Settings;
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LEDs;
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Display Panel;
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Zone Interlocking Function;
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Power Relay Module;
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Rating Plug; and
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Communications Functions .
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There are some parts it cannot check, for example:
Current Sensors;
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Auxiliary Current Transformers;
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Bridge Circuits;
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Calibration Resistors;
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Potential Transformer Module;
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Analog Override Circuit;
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and the functions of these elements are best verified by primary cur-
rent injection testing .
As indicated in Figure 20, Note 1, six different "Test Amps" settings
(1, 2, 3, 6T, 8 and 10 x I ) are available for testing the phase ele-
n
ments of the Trip Unit, and two settings (GF and GFT) are provided
for testing the ground element .
CAUTION
A SETTING OF EITHER 6T OR GFT WILL TRIP THE CIRCUIT BREAKER (SEE
SECTIONS 4.1 AND 4.4.2.).
FOR ANY COMBINATION OF THE PHASE PROTECTION SETTINGS, AN
APPROPRIATE "NO TRIP" CONDITION CAN BE SET TO TEST THE LONG
TIME, SHORT TIME, AND INSTANTANEOUS TRIP SETTINGS WITHOUT
TRIPPING THE CIRCUIT BREAKER (SEE SECTION 4.4.1).
IN THE "GF" TEST POSITION, THE LEVEL OF TEST CURRENT, BASED ON I
IS ADEQUATE TO DEMONSTRATE THE OPERATING CONDITION OF THE TRIP
UNIT WITHOUT TRIPPING THE CIRCUIT BREAKER. THIS IS A FUNCTIONAL
CHECK ONLY, NOT A CALIBRATION.

4.4 Conducting Tests

To preserve the primary protection function of the Trip Unit, all in-ser-
vice testing whether under "Trip" or "No-Trip" conditions is executed
ONLY if load current values are no greater than 50% x I
Long Delay Current Setting) . Any attempt to conduct in-service
testing when the load current exceeds 50% of I
executed by the Trip Unit.
Since the Digitrip RMS 910 Trip Unit is designed to run with control
power from the Power / Relay Module for the display window and
communications functions, all testing should be conducted with the
control power available, either through the Power Relay Module or,
when the breaker is outside the enclosure, through the Auxiliary
Power Module (APM) (see Section 1 .6 and Figure 12) . Although the
Trip Unit is designed to perform all of its Protection Functions with-
out the external control power, and without the display and commu-
nication functions available, results of the tests could be confusing .
When performing a single-phase primary current injection tests, for
example, especially when the single-phase current is low, without
the APM it may appear as if the Trip Unit does not respond until
20
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the current is well-above the set value, leading the tester to believe
there is an error in the Trip Unit when there is none . The reason this
occurs is that the single-phase test current is not a good simulation
of the normal three-phase circuit . If three-phase current had been
flowing, the Trip Unit would actually have performed correctly . Use
the APM for correct Trip Unit performance whenever single-phase
current injection tests are made .
1. Before starting any test sequence, check the Unit Status
(Green LED) in the lower right corner of the Trip Unit (see Figure.
I and 20) to be sure it is blinking on and off about once each sec-
ond, which indicates that the Trip Unit is functioning normally. In
the event the Unit Status LED is not blinking, install an Auxiliary
Power Module (APM) (see Figure 12), or if you have already
installed one, check to see that it is connected correctly (see
Section 1 .6) .
2. If the circuit breaker is carrying current, check that the cur-
rent is not more than 50% of the Long Delay Current Setting (I
because the Trip Unit will not execute your test instructions
when it senses that the current through the breaker exceeds
the 50% level. If the current through the circuit breaker
increases to a value greater than 50% of the Long Delay
Current Setting, I
Trip Unit Test that may be in progress. Should an actual
overload or fault condition occur during an in-service, test
sequence, the protection function will override the test func-
tion, and the circuit breaker will trip automatically in accor-
dance with the actual Time-Current settings.
3. When performing tests on the Long Delay element, be aware
that in addition to the standard protection element, the
Digitrip RMS 910 Trip Unit also has a Long Time Memory
function (LTM), which serves to protect load circuits from
the effects of repeated overload conditions (see Note 1 under
Section 3 .3 Long Delay Time Setting) . The action of the LTM
during primary injection tests and during tests initiated from the
Trip Unit Test Panel under the "TEST AMPS" setting of "6T", will
advance the Long Delay Trip Time if multiple Long Delay Time
tests are performed repeatedly - as one might do in making
single-phase tests on each pole of a breaker in succession, for
example . If there is any question, you may simply wait about
ten (10) minutes after a Long Delay Trip for the LTM to reset .
The LTM is not active during tests initiated from the Trip Unit Test
Panel under the "TEST AMPS" settings of "I", "2", "3", "8", or "10" .
To reset the LTM immediately:
Set the "TEST AMPS" to "1" .
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, Press and release the (Black) "TEST" push-button (timer will be
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N
running in the display window), and then
Quickly press and release the "TRIP RESET" push-button
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before the Trip Unit operates .
Now the LTM will be reset .
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4. When performing tests on the Ground Fault element, be
aware that in addition to the standard protection, the
Digitrip RMS 910 Trip Unit also has a Ground Time Memory
(I = the
r r function (GTM), which serves to protect load circuits from the
effects of repeated (sputtering) ground arcs (see Note under
, will NOT be
Section 3 .9 Ground Fault Time Delay Setting) . Because the GTM
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resets quickly, it will not normally affect ground fault test results,
but if Ground Fault tests are repeated quickly, the GTM can
make the breaker appear to trip too soon .
N otee: To STOP a TEST initiated via the integral test panel PRESS AND
RELEASE THE "TRIP RESET" PUSH-BUTTON .
Instructions for Digitrip RMS 910 Trip Unit
, the Trip Unit will automatically abort any
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