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Instruction Book
Page 20
Effective: May 2006
3-6 ELECTRONIC TRIPPING SYSTEM
The Magnum DS/DSX/DSL circuit breakers utilize a
three part tripping system (Figure 3-17):
• Microprocessor-based trip unit
• Current Sensors
• Trip Actuator
All three parts of the tripping system are discussed
here, except that the trip unit itself is not discussed in
detail. For detailed information pertaining to the differ-
ent trip unit models available with Magnum
DS/DSX/DSL circuit breakers, refer to the specific
instruction leaflet dedicated to the trip units (I.L.
70C1036 and I.L. 70C1037 ).
3-6.1 MICROPROCESSOR-BASED TRIP UNIT
Magnum circuit breakers use any one of a family of
Digitrip RMS trip units whose main features are summa-
rized in Table 3.1. Also, the MDSX family of breakers is
intended to be used only with trip units manufactured
after May 1, 2005.
Models 520 is plug compatible and interchangeable in
the field. Circuit breakers with these trip units can be
upgraded to Models 520M and/or 520MC in the field;
however additional wiring (for power supply and com-
munications) may be required to take full advantage of
the additional features. Contact Cutler-Hammer for
upgrading to Model 1150.
The electronic trip units are self-powered. When the cir-
cuit breaker is closed, no external power is required to
operate their protective systems. Current signal levels
and the control power are derived from the current sen-
sors integrally mounted in the circuit breaker.
A functional local test of a major portion of the trip unit's
electronic circuitry and the circuit breaker's mechanical
tripping action can be verified through the trip unit's test
receptacle (Figure 3-18). This is accomplished using a
Digitrip (DS Type) Test Kit which provides a secondary
injection test that simulates the current sensors. A
small hand held Magnum functional Test Kit can also be
used to check circuitry and mechanical tripping func-
tions (Figure 3-19).
When the circuit breaker is shipped from the factory, the
trip unit's protective functions are normally set at mini-
mum values. For specific overload tripping characteris-
tics and time/current curves to coordinate with a load or
system, refer to the trip unit instruction book.
Figure 3-17 Pictorial Diagram of Typical Current
Sensing, Processing and Tripping System
Table 3.1 Magnum Digitrip Trip Units
➀ One-line, (four characters per line) LCD display.
➁ Three-line, (eight characters per line) LED display.
➂ Phase, neutral, ground, and high load current only.
➃ Available control voltages are 24/48Vdc, 125Vdc, 120Vac and
For more information visit: www.EatonElectrical.com
Trip Unit
Toroidal
Current
Sensor
01
02
03
A
B
C
A
B
C
N
G
N
Note: Alternate ground locations
520M ➃ 520MC ➃ 1150 ➃
Functions
520
LSIG Protection
Yes
Yes
Disable (I)
Yes
Yes
GF Protection
Yes
Yes
GF Alarm
No
Yes
Display
No
Yes ➀
Programmable
No
No
Metering
No
Yes ➂
Power and
Energy Values
No
No
Power Quality
No
No
Communication
No
No
240Vac
Cutler-Hammer
Rating Plug
Trip
Actuator
Typical Magnum DS
Circuit Breaker
Sensors
may be required to meet
installation requirements
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes ➀
Yes ➁
No
Yes
Yes ➂
Yes
No
Yes
No
Yes
Yes
Yes
I.B. 2C12060H08
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