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MaGnuM PRoDuct GuiDe
CA013002EN—April 2017 www.eaton.com
23
Magnum DS - Product specific information
Magnum DS - Current limiting
circuit breakers
MDSL circuit breaker
Magnum MDSL current limiting power circuit breakers utilize
integral current limiters to provide interruption ratings of 200
kA at 600 Vac with continuous limitation with lower let through
currents for superior protection of downstream equipment .
The MDSL breaker is available only in a drawout configuration .
Current limiters are held in place in a 6 inch (152 .4 mm) extension
provided on the back of the circuit breaker . The current limiters
can only be removed from the breaker and replaced when the
MDSL breaker is removed from its associated compartment .
A blown limiter indicator provides a visual indication on the front
of the MDSL when a current limiter in any phase has interrupted
a short circuit . The indicator itself is a red pop-out button located
on the lower left portion of the breaker’s front cover .
The direct trip actuator trips the circuit breaker, and an output to
the indicator causes the button to pop out .
Current limiter selection
Current limiters can be selected from the current limiter selection
table (Table 7) and are categorized for selection in three ways:
•
Minimum current limiter
•
Recommended current limiter
•
Maximum current limiter
The selection of a suitable limiter rating for a given application
is generally governed by a choice of the following two types of
protection:
(A) Maximum protection of downstream components:
Type MDSL breakers are often used for this purpose even when
the maximum available fault currents are within the interruption
rating of the corresponding unfused Magnum breakers .
(B) Protection of circuit breaker only:
Case A would tend to use the smallest available limiter; Case B
the largest .
Table 7 . Magnum MDSL sensor/rating plug vs . Current limiter selection
Sensor and
Rating plug i
n
MDSl current limiter selection chart
200
MA250
MA300
MA400
MA600
MA800
MB1200
MB1600
MB2000
MD2500
MD3000
250
MA400
MA600
MA800
MB1200
MB1600
MB2000
MD2500
MD3000
300
MA400
MA600
MA800
MB1200
MB1600
MB2000
MD2500
MD3000
400
MA600
MA800
MB1200
MB1600
MB2000
MD2500
MD3000
600
MA800
MB1200
MB1600
MB2000
MD2500
MD3000
800
MB1200
MB1600
MB2000
MD2500
MD3000
1000
MB1600
MB2000
MD2500
MD3000
1200
MB2000
MD2500
MD3000
1600
MD3000
2000
MD3000
Select the current limiter based on the Magnum breaker frame and current sensor and rating plug as shown .
Refer to MDSL current limiter curves for let-through and time characteristics .
The recommended ratings provide for reduced current let-through and breaker coordination within the trip unit settings . Selection of current limiters
below the recommended ratings shown provides lower current let-through, however, trip unit settings must be considered to avoid nuisance
operation .
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Current limiter
Blown
limiter
indicator