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
U L Listed Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.0
Principle of Operation . . . . . . . . . . . . . . . . . . . . . . . .
3.1
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.2
Trip and Operation Indicators . . . . . . . . . . . . . . . . .
3.3
Test Provisions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.4
Making Current Release (Discrim inator) . . . . . . .
3.5
I nstantaneous Override . . . . . . . . . . . . . . . . . . . . . .
3.6
Zone I nterlocking . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.0
Protection Settings . . . . . . . . . . . . . . . . . . . . . . . . . . .
4 . 1
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.2
Long Delay Settings . . . . . . . . . . . . . . . . . . . . . . . . .
4.3
Long Delay Time Settings . . . . . . . . . . . . . . . . . . . .
4.4
Short Delay Pick-up Settings . . . . . . . . . . . . . . . . .
4.5
Short Delay Time Settings . . . . . . . . . . . . . . . . . . .
4.6
I nstantaneous Pick-u p Settings . . . . . . . . . . . . . . .
4.7
G round Fault Cu rrent Pick-u p Settings . . . . . . . .
4.8
G round Fault Time Delay Settings . . . . . . . . . . . .
5.0
I nteg ral 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 Tripping the B reaker . . . . . . . . . . . . . . . . . . . . . .
6.0
Back-up Battery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6. 1
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.2
Battery Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.3
Battery Replacement . . . . . . . . . . . . . . . . . . . . . . . . .
7.0
Auxi liary Power Module . . . . . . . . . . . . . . . . . . . . . .
8.0
Rati ng Plug . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.0
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.1
Type OS Low Voltage AC Power Circuit
Breakers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.2
Type SPB Systems Pow-R Breakers . . . . . . . . . . .
9.3
Digitrip RMS Trip Assembl ies . . . . . . . . . . . . . . . .
9.4
Series C® R-Frame Molded Case Circuit
Breakers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
WARNING
DO NOT ATTEMPT TO I N STALL OR PERFORM MAIN
TENANCE ON EQUIPMENT WHILE IT IS ENERG IZED.
DEATH OR SEVERE PERSONAL INJ URY CAN RESULT
FROM CONTACT WITH E N E RGIZED EQUIPME NT.
ALWAYS VERIFY THAT NO VOLTAG E IS PRESENT
B E F O R E P R O C E E D I N G W I T H THE TAS K , A N D
ALWAYS FOLLOW G E N ERALLY ACCEPTED SAFETY
PROCE D U R E S . THE WESTI N G H O U S E ELECTR I C
CORPORATION IS NOT LIABLE FOR THE MISAPPLI
CATION OR MISINSTALLATION OF ITS PRODUCTS.
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The user is cautioned to observe a l l recommendations, warn
ings and cautions relating to the safety of personnel and equip
ment. as well as all general and local health and safety laws,
codes, and procedures.
The recommendations and information contained herein a re
based on Westinghouse experience and judg ement, 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 al l-inclusive or covering every appli
cation o r circumstance which may arise. If any questions arise,
contact Westi nghouse Electric Corporation for further i nfor
mation or i n structions.
1 .0 General Description
1 . 1 Protection
The Digitrip R M S 500 Trip U nit, illustrated i n Fig. 1 , is a m icro
processor based type trip su itable 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 unit provides true RMS current sensing for proper
correlation with thermal characteristics of conductors and
equipment. I nterchangea ble rating plugs are provided to estab
lish the continuous current rating of each circuit breaker.
The Digitrip RMS 500 Trip Unit is completely self-contai ned
and when the circuit breaker is closed, requ i res no external
control power to operate its
protection systems.
It operates
from cu rrent signal level s and control power derived through
current sensors i ntegrally mounted in the circuit breaker.
The Digitrip RMS 500 Trip Unit is available in six optional pro
tection models. Each trip unit may be equ ipped with a maxi
mum of five phase and two g round (time-current) adjustments
to meet specific appl ication requi rements. These protection
models i nclude the fol lowing types which a re further illus
trated in the nameplate examples shown in Fig. 2.
Figure
Type Protection
2.1
Long Time/Instantaneous
2.2
Long Time/Short Time
2.3
Long Ti me/Short Time/I nstantaneous
2.4
Long Time/I nstantaneous/Ground
2.5
Long Time/Short Time/G round
2.6
Long Time/Short Time/Instantaneous/
G round
1 .2 Information
Identifier
(LI)
(LS)
(LSI)
( LIG )
(LSG)
(LSIG)
Red LED indicators are provided on the face of the trip unit
to indicate the mode of a n automatic trip operation. A bat
tery is provided to maintain the mode of trip LED indication
fol lowi ng an automatic trip operation.
G reen LEOs are provided to indicate the operational status of
the trip unit and the status of the back-up battery mou nted i n
the rating p l u g .
1 .3 Testing
An i ntegra l test panel, i ncluding a test selector switch and test
and reset pushbuttons, is provided to test the circuit breaker
i n either a "Trip" or "No-Trip" test mode under qualified
conditions.
2.0 UL Li�ted Devices
Digitrip RMS 500 Trip U n its are l i sted by the Underwriters
Laboratories, Inc. for use in types SPB, DS and DSL and
Series C R-Frame ci rcuit breakers under U L File E781 9.
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