Effective 7/1/2003
Page 29
I.L. 70C1037H04
interior of the breaker cell door or another visible location.
Figure 8.3 provides a place for recording test data and
actual trip values.
Ideally, sheets of this type should be used and maintained
by those personnel in the user’s organization that have the
responsibility for protection equipment.
9.0 REFERENCES
9.1 Magnum and Magnum DS Circuit Breakers
I.B. 2C12060
Magnum DS Breaker Instructions
I.B. 2C13060
Magnum I. Breaker Instructions
4A36346
Zone Interlocking Application with Non-
Magnum Breakers
I.L. 66A7508
Instruction for mMINT Modbus Translator
Module
9.2 Time-Current Curves
The Time-Current Curves are listed below for particular trip
unit models. All protection function time-current settings
should be made following the recommendations of the
specifying engineer in charge of the installation.
70C1009
Digitrip 220 (LI) Curve
70C1295 Digitrip 220+ (L) Curve
70C1296 Digitrip 220+ (I) Curve
70C1006
Digitrip 520 (LS) Curve
70C1007
Digitrip 520 (I) Curve
70C1008
Digitrip 520 (G) Curve
7.0 FRAME RATINGS (SENSOR RATINGS AND RATING PLUGS)
The frame rating
of a circuit breaker is the maximum RMS
current it can continuously carry. The maximum short-
circuit current rating of the circuit breaker is usually related
to the frame rating as well.
A current value, (
I
n), that is less than the full frame rating
may be chosen to be the basis for the coordination of the
protection function of the breaker without affecting its
short-circuit current capability. For the Digitrip 520 family of
trip units, this is implemented by changing the current
sensors
and the corresponding
rating plug. These sensors
and rating plugs are available in kit form.
The current sensor rating is the maximum current the
circuit breaker can carry with the specified current sensors
installed. The sensor rating can be the same or less than
the frame rating, but not greater.
This value, (
I
n), is the basis for the trip unit current set-
tings:
1. The Instantaneous and Ground Current Settings (if
provided) are multiples of (
I
n) (see Sections 4.6
and 4.7).
2. The Long Delay Current Setting, (
I
r), is a fractional
multiple of (
I
n): Long Delay Current Setting = (
I
r) = LD
x (
I
n) (see Section 4.2).
3. The Short Delay Current Setting is a multiple of (
I
r):
Short Delay Current Setting = SD x (
I
r) = SD x [LD x
(
I
n)] (see Section 4.4).
CAUTION
BEFORE YOU FIT THE RATING PLUG INTO THE TRIP
UNIT, BE SURE TO CHECK THAT EACH BREAKER
POLE SENSOR RATING MATCHES THAT PRINTED ON
THE RATING PLUG DOOR. INSTALLING A RATING
PLUG THAT DOES NOT MATCH THE SENSOR RATING
CAN PRODUCE SERIOUS MISCOORDINATION AND/OR
FAILURE OF THE PROTECTION SYSTEM.
NOTE:
Rating plugs from Digitrip models 210, 500, or 510
CANNOT
be used with 520 family model Trip Units.
8.0 RECORD KEEPING
Use the forms shown in Figures 8.1 and 8.2 for record
keeping. Fill in these forms, giving the indicated reference
information and initial time-current trip function settings. If
desired, make a copy of the form and attach it to the
