32
Instructional Leaflet
IL70C1037H05
Effective October 2009
Digitrip models 520, 520i; and 520M, 520Mi,
520MC, 520MCi trip units for use only in
Magnum and Magnum DS circuit breakers
eaton corporation
www.eaton.com
Section 10: Digitrip 520Mc with
Maintenance Mode
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WARNING
ONLY CERTIFIED AND COMPETENT PERSONNEL SHOULD ATTEMPT
TO INSTALL OR MAINTAIN POTENTIALLY HAZARDOUS EQUIPMENT.
DO NOT ATTEMPT TO INSTALL OR PERFORM MAINTENANCE ON
EQUIPMENT WHILE IT IS ENERGIZED. DEATH OR SEVERE PERSONAL
INJURY CAN RESULT FROM CONTACT WITH ENERGIZED EQUIPMENT.
ALWAYS VERIFY THAT NO VOLTAGE IS PRESENT BEFORE PROCEEDING.
ALWAYS FOLLOW SAFETY PROCEDURES. EATON IS NOT LIABLE FOR THE
MISAPPLICATION OR MISINSTALLATION OF ITS PRODUCTS.
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CAUTION
OBSERVE ALL RECOMMENDATIONS, NOTES, CAUTIONS, AND WARNINGS
RELATING TO THE SAFETY OF PERSONNEL AND EQUIPMENT. OBSERVE
AND COMPLY WITH ALL GENERAL AND LOCAL HEALTH AND SAFETY
LAWS, CODES, AND PROCEDURES.
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CAUTION
A FLASH HAZARD ANALYSIS SHOULD BE DONE TO DETERMINE PERSONAL
PROTECTIVE EQUIPMENT REQUIREMENTS.
Gtntral
Per the above WARNING, it is highly recommended that
maintenance be conducted on electrical equipment, including
circuit breakers with the system de-energized.
For situations that arise where this is not possible, the Maintenance
Mode function of the Digitrip 520MC family (
Cat. 5ARMLSI,
5ARMLSIG, 5ARMLSIA
) can reduce arc flash incident energy that
is generated on a fault condition. This is accomplished by an analog
trip circuit which, when armed, provides a fast-acting response
to the fault. The reduced arc condition will occur only in devices
downstream of the trip unit in Maintenance Mode. This is separate
from the normal system protection setting of Instantaneous. The
Maintenance Mode is located in the upper, white portion of the unit.
Mainotnanct MNdt stooings
The Maintenance Mode settings (labeled R5, R4, R3, R2, R1)
provide the Arc Flash Reduction setting. R5 is the maximum
reduction setting, which correlates to the lowest pickup value.
Nominal trip current of Maintenance Mode settings:
Setting R5
2.5 x Rating Plug Amperes
Setting R4
4.0 x Rating Plug Amperes
Setting R3
6.0 x Rating Plug Amperes
Setting R2
8.0 x Rating Plug Amperes
Setting R1
10.0 x Rating Plug Amperes
Arming Mainotnanct MNdt
There are three ways to arm the Maintenance Mode Arc Flash
Reduction setting. One method is locally via the two-position switch
in the Maintenance Mode section of the trip unit. Turning the
switch to the ON position will arm the setting selected. A blue LED
confirms that the function is on.
For the other two methods of arming the Maintenance Mode
function, this switch must be in the position labeled 0/1. With this
setting, a remote switch wired through the breaker secondary
contacts can remotely arm the Maintenance Mode setting. A
high quality, gold-plated or palladium contact is required in this
application. The blue LED will verify that the function is armed.
(See wiring diagram
Figurt 47
.)
A third method to arm the Maintenance Mode setting is via a
communication device. A Palm Pilot along with an IR MINT device
can be employed to arm the setting. By initiating the ENABLE
setting, the Maintenance Mode selection in the control screen of
the Palm, Maintenance Mode is set. There is a confirmation screen
that verifies the arming. A BIM (Breaker Interface Module) is another
communication method to arm the setting. When Maintenance
Mode setting is enabled via device communications, this setting
must be disabled by device communications.
RtmNot indicaoNr
The Magnum circuit breaker will be wired with secondary contacts
A9 and A12. Circuit breakers built after September 2005 have a
normally open contact available to customer use. This contact can
be used to indicate remotely that the Maintenance Mode setting
is armed. Refer to diagram below for a wiring of this remote (blue
light) indicator.
ChNNsing oht rtducoiNn stooing
The Arcflash Reduction Maintenance System is an eight-position
rotary switch that has five unique settings. Setting R5 is repeated
four times. From the factory, the Magnum circuit breaker is shipped
with the Digital unit set to the R5 setting and with its arming switch
set to the 0/1 position. The 0/1 position means that it is locally
OFF, but can be remotely turned ON. The blue LED, if illuminated,
provides indication that the Maintenance Mode setting is armed
per one of the three methods described on page 32. In general, the
selection of one of the Reduction Settings (R5 through R1) should
be determined and selected by a person who is experienced in
power system analysis.
This setting choice normally does not change unless there are future
system modifications that could increase or decrease fault levels at
the circuit breaker location.
Tripping and otsoing
The Maintenance Mode function will provide fast tripping even when
the regular Instantaneous is set to OFF. The Instantaneous LED
position is also used to indicate a trip initiated by the Maintenance
Mode setting. The LCD display, if powered, will indicate this with
four dashes.
The Maintenance Mode setting, external wiring (if any), and tripping
functionality should be periodically verified by primary or secondary
injection current testing.
