Siemens I-T-E Sensitrip MD Series, Information And Instruction Manual

Page: 11 / 63

MD and ND-Frame Trip Adjustments
9
Figure 1
I
n
= Maximum circuit breaker ampere rating.
I
r
= Current Rating—a function of continuous ampere adjust-
ment setting expressed in % of I
n
Adjustable Instantaneous Trip Switch
x I
r
Instantaneous settings are multiples of the continuous cur-
rent setting.
NOTE: Maximum instantaneous trip is 10,000 Amps—with
instantaneous setting on “MAX”, time delay is eliminated.
I
g
= Ground Fault Pickup—a function of adjustment setting
expressed in % of I
n
.
Adjustable Ground Fault Pickup
Pickup I
g
=%I
n
Delay 1 2 t @ 51n
Ground fault protection is available for 3 phase, 3 wire and 3
phase 4 wire (neutral) electrical systems. SMD/SND models
with an adjustable ground fault delay switch allow for the
selection of ground fault pickup at 20, 25, 30, 40, 55 or 70%
of the maximum amps rating (%I
n
), with an 1
2
t delay of .1, .2,
or .4 sec @ .5 x I
n
See Figure 1 for possible settings for this
switch