Instructions for
Digitrip RMS 500 Trip Unit
Table of Contents
1 .0
General Description . . . . . . . . . . . . . . . . . . . . . . . . . .
1 . 1
Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1 .2
Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1 .3
Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.0
UL Listed Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.0
Principle of Operation . . . . . . . . . . . . . . . . . . . . . . . .
3.1
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.2
Trip and Operation Indicators . . . . . . . . . . . . . . . . .
3.3
Test Provisions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.4
Making Cu rrent Release (Discrimi nator) . . . . . . .
3.5
Instantaneous Override . . . . . . . . . . . . . . . . . . . . . .
3.6
Zone Interlocki ng . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.0
Protection Settings . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.1
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.2
Long Delay Settings . . . . . . . . . . . . . . . . . . . . . . . . .
4.3
Long Delay Time Setti ngs . . . . . . . . . . . . . . . . . . . .
4.4
Short Delay Pick-up Settings . . . . . . . . . . . . . . . . .
4.5
Short Delay Time Settings . . . . . . . . . . . . . . . . . . .
4.6
Instantaneous Pick-up Settings . . . . . . . . . . . . . . .
4.7
G round Fault Cu rrent Pick-up Setti ngs . . . . . . . .
4.8
G round Fault Time Delay Settings . . . . . . . . . . . .
5.0
Integral Test Panel - Test Procedu re . . . . . . . . . .
5.1
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.2
When To Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3
Test Provision . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.4
Mode of Conducting Tests . . . . . . . . . . . . . . . . . . .
5.4.1
Control Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.4.2
By Not Tripping the Breaker . . . . . . . . . . . . . . . . . .
5.4.3
By Tri pping the Breaker . . . . . . . . . . . . . . . . . . . . . .
6.0
Back-up Battery . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
.
6.1
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.2
Battery Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.3
Battery Replacement . . . . . . . . . . . . . . . . . . . . . . . . .
7.0
Auxiliary Power Module . . . . . . . . . . . . . . . . . . . . . .
8.0
Rati ng Plug . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.0
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.1
Type DS Low Voltage AC Power Circuit
Breakers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.2
Type SPB Systems Pow-R Breakers . . . . . . . . . . .
9.3
Dig itrip RMS Trip Assem bl ies . . . . . . . . . . . . . . . .
9.4
Series C® R-Frame Molded Case Circuit
Breakers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
WARNING
DO NOT ATTEMPT TO I N STALL OR PERFORM MAIN
TENANCE ON EQU IPMENT WHILE IT IS E N E RGIZED.
DEATH OR SEVERE PERSONAL INJ U RY CAN RESULT
FROM CONTACT WITH E N ERG IZED EQUIPME NT.
ALWAYS VER I FY THAT NO VOLTAGE IS PRESENT
B E F O R E P R O C E E D I N G W I T H T H E TAS K , A N D
ALWAYS FOLLOW G E N ERALLY ACCEPTED SAFETY
P R OC E D U R E S . T H E WESTI N G H O U S E ELECTR I C
CORPORATION IS N OT LIABLE F O R T H E MISAPPLI
CATION OR MISINSTALLATION OF ITS PRODUCTS.
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The user is cautioned to observe all recommendations, warn
i ngs and cautions relating to the safety of personnel and equip
ment, as wel l as all general and local health and safety laws,
codes, and procedures.
The recommendations and i nformation contained herein are
based on Westi ng house experience and judgement, but should
Effective May, 1 989 Supersedes I . L. 29-851 dated March, 1 988
I.L. 29-851-A
not be considered to be a l l -incl usive or covering every appli
cation or circumstance which may a rise. lf,any questions arise,
contact Westinghouse Electric Corporation for further infor
mation or instructions.
1 .0 General Description
1 . 1 Protection
The Digitrip R M S 500 Trip U n it, illustrated in Fig. 1 , is a micro
processor based type trip suitable for use in type SPB Systems
Pow-R circuit breakers and types DS and DSL low voltage AC
power circuit breakers and Series C® R-Frame molded case
circuit breakers.
The trip u n'it provides true RMS current sensing for proper
correlation with thermal characteristics of conductors and
equi pment. I nterchangeable rating p l ugs are provided to estab
lish the contin uous current rating of each circuit breaker.
The Digitrip RMS 500 Trip U n it is completely self-contained
and when the circuit breaker i s closed, requ i res no external
control power to operate its
protection systems.
It operates
from current signal levels and control power derived through
current sensors i ntegrally mounted in the circuit breaker.
The Digitrip RMS 500 Trip U nit is available in six optional pro
tection models. Each trip unit may be equi pped with a maxi
mum of five phase and two g round (time-current) adjustments
to meet specific application requ i rements. These protection
models include the fol lowi ng types which are further i l l us
trated in the nameplate examples shown in Fig. 2.
Figure
Type Protection
2 . 1
Long Time/Instantaneous
2.2
Long Time/Short Ti me
2.3
Long Time/Short Time/Instantaneous
2.4
Long Time/Instantaneous/G round
2.5
Long Time/Short Time/Ground
2.6
Long Time/Short Time/I nstantaneous/
G round
1 .2
Information
Identifier
(LI)
(LS)
(LSI)
(LIG)
( LSG)
(LSI G)
Red LED indicators are provided on the face of the trip unit
to indicate the mode of an automatic trip operation. A bat
tery is provided to maintain the mode of trip LED indication
fol lowing an automatic trip operation.
Green LEOs are provided to indicate the operational status of
the trip u nit and the status of the back-up battery mounted i n
the rating plug.
1 .3 Testing
An integral test panel, i ncluding a test selector switch and test
and reset pushbuttons, is provided to test the circuit breaker
in either a "Tri p" or " No-Trip" test mode under qual ified
conditions.
2.0 UL Listed Devices
Digitrip R M S 500 Trip U nits are l i sted by the U n derwriters
Laboratories, I nc. for use in types SPB, DS and DSL and
Series C R-Frame circuit breakers u nder U L File E78 1 9.
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