I.B. 29C891B
Page 25
Effective 11/98
• If it is later determined that the Long Delay Setting (I
r
)
is to be 140 amperes in lieu of the original 100
amperes. The Long Delay Setting (I
r
) can be re-pro-
grammed to 0.7 (I
n
) = 0.7 (200) = 140 amperes, the
new required Long Delay Setting (I
r
).
• The re-programming change to the Long Delay
Setting (I
r
) alters the Short Delay Pickup originally pro-
grammed, since the Short Delay Pickup is a function
of the Long Delay Setting (I
r
). The new Short Delay
Pickup = 2.0 (I
r
) = 2.0 (140) = 280 amperes. This new
Short Delay Pickup may or may not be acceptable. If it
isn’t, it will also have to be re-programmed.
3-2.3 PROTECTION AND CURVE SHAPING
FEATURES
There are three different OPTIM Trip Unit configurations:
• LSI (Except on Model 750 and 1050 K, L and N-
Frame breakers)
• LSIA
• LSIG
LSI Configuration
The LSI configuration provides a required long delay pro-
tection and a user selectable short delay protection
Figure 3-4 Overcurrent Protective Function
Combinations
L S I
Required
User Selectable
Optional
(Either S or I
or Both)
POSSIBLE COMBINATIONS
LI
LIG
LS
LSG
LSI
LSIG
LSIA
and/or instantaneous protection. Modals 750 and 1050
achieve LSI by turning off the “A” feature on the LSIA unit.
LSIA Configuration
The LSIA configuration provides the same protective
functions described for the LSI configuration plus it
senses ground fault conditions and provides for a local
or remote alarm of the condition. It does not trip the cir-
cuit breaker due to a ground fault condition. The alarm
feature can be turned OFF if desired.
LSIG Configuration
The LSIG configuration provides the same protective
functions described for the LSI configuration plus
ground fault protection. It senses ground fault conditions
and trips the circuit breaker. If a local ground alarm
contact is present, it actuates also.
For any of the three configurations described, the short
circuit functions (short delay and instantaneous) are
user selectable using the OPTIMizer, Breaker Interface
Module or Series III Software as follows:
• Both short delay and instantaneous enabled
• Only short delay enabled
• Only instantaneous enabled
Notice:
Short delay and instantaneous cannot be dis-
abled at the same time.
The three trip unit configurations are available by circuit
breaker type as follows (Tables
3.2
and
3.3
):
• Series C L and N-Frame (LSIA and LSIG)
• Series C K-Frame, R-Frame, SPB Pow-R and
DSII/DSLII (LSI, LSIA and LSIG)
All Digitrip OPTIM Trip Units are available in six overcur-
rent protective function combinations of long, short,
instantaneous and ground (Figure
3-4
). When the pro-
tection functions are combined with slope adjustments
I
4
t, I
2
t or Flat, the Digitrip OPTIM Trip Unit provides the
following ten programmable curve shaping possibilities:
• Overload
- Long Delay Setting
- Long Delay Time, I
2
t Response
- Long Delay Time, I
4
t Response
• Short Circuit
- Short Delay Pickup
- Short Delay Time, Flat Response
- Short Delay Time, I
2
t Response
- Instantaneous
A G
or
Summary of Contents for Digitrip OPTIM 1050
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