Cutler-Hammer Digitrip RMS 510, Инструкция по эксплуатации

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Page 4
Fig. 2.5 Long Time/Short Time/Ground/Protection
(LSG)
1 .3 Testing
To test the trip u nit, use the i ntegral test panel. (See Sec­
tion 5.0.)
2.0 UL LISTED DEVICES
Digitrip RMS
5 1 0
Tri p U n its are "Listed" by the U nderwrit­
ers Laboratories, I nc.® U nder U L File E781 9, for use in
types OS, DSL, SPB and Series c® R-Frame circuit
breakers.
3.0 PRINCIPLES OF O PERATION
3.1 General
The Digitrip RMS 51 0 trip unit is designed for use i n
industrial circuit breaker environments where the ambient
temperatures can range from -20 C to
+as
C and rarely
exceed 70 to 75 C. If, however, temperatures in the
neighborhood of the trip u nit do exceed this range, the
trip unit perfo rmance may be degraded. In order to insure
that the tripping function is not compromised due to an
over-temperatu re condition, the Digitrip RMS 5 1 0 micro­
computer chip has a built-in over-temperature protection
feature, factory set to trip the breaker if the chip tempera­
ture exceeds 95 C. If over-temperature is the reason for
the trip, the Long Delay Time LED will light "RED".
I.L. 29-8858
Fig. 2.6 Long Time/Short Time/Instantaneous/Ground
Protection (LS/G)
The Digitrip RMS 51 0 Trip unit provides three basic func­
tions: Protection, Information and Testing. A typical trip
unit and rating plug are illustrated in Fig. 1 . Individual
product instruction leaflets referenced in Section 9.0 illus­
trate typical Digitrip RMS Trip Units installed in specific
breakers.
The trip unit employs the Cutler-Hammer Inc. custom
designed integrated circuit S)lRE + chip, which includes a
microcomputer to perform its numeric and logic fu nctions.
The principle of operation is described by the block d ia­
gram shown in Fig. 3.
In the Digitrip RMS 5 1 0 Trip U nit, all required sensing and
tripping power to operate its
protection function
is
derived from the cu rrent sensors in the ci rcuit b reaker.
The secondary currents from these sensors provide the
correct input information for the protection functions, as
well as tripping power, whenever the circuit breaker is
carrying current. These current signals develop analog
voltages across the appropriate calibrating resistors
including:
1 ) Phase currents
2) Ground current (when supplied)
3) Rating plug
The resulting analog voltages are digitized by the custom
designed integrated circuits.
Effective May 1 997
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