Schneider Electric 3.0A User Manual
48049-136-05
Micrologic™ 2.0A, 3.0A, 5.0A, and 6.0A Electronic Trip Units
Rev. 01, 07/2012
Section 1—General Information
© 1999–2012 Schneider Electric All Rights Reserved
11-EN
EN
G
L
ISH
Short-Time Protection
Short-time protection protects equipment
against short circuits.
against short circuits.
•
Short-time protection is standard on 2.0A,
5.0A and 6.0A trip units. It is not available on
3.0A trip units.
5.0A and 6.0A trip units. It is not available on
3.0A trip units.
•
Short-time protection is based on the long-
time pickup (Ir).
time pickup (Ir).
•
The short-time pickup (Isd) (A) sets current
level (below instantaneous trip level) at
which circuit breaker will trip after the preset
time delay.
level (below instantaneous trip level) at
which circuit breaker will trip after the preset
time delay.
•
The short-time delay (tsd) (B) sets the length
of time that the circuit breaker will carry an
overcurrent above the short-time pickup
current level before tripping. It is adjustable
on the 5.0A and 6.0A trip unit and factory set
to zero on the 2.0A trip unit.
of time that the circuit breaker will carry an
overcurrent above the short-time pickup
current level before tripping. It is adjustable
on the 5.0A and 6.0A trip unit and factory set
to zero on the 2.0A trip unit.
•
The I
2
t on/I
2
t off option provides improved
selectivity with downstream protective
devices:
devices:
— With I
2
t off selected, fixed time delay is
provided.
— With I
2
t on selected, inverse time I
2
t
protection is provided up to 10 x Ir.
Above 10 x Ir, fixed time delay is
provided.
Above 10 x Ir, fixed time delay is
provided.
•
Intermittent currents in the short-time tripping
range which do not last sufficiently long to
trigger a trip are accumulated and shorten
the trip delay appropriately.
range which do not last sufficiently long to
trigger a trip are accumulated and shorten
the trip delay appropriately.
•
Short-time protection can be zone-selective
interlocked (ZSI) with upstream or
downstream circuit breakers.
interlocked (ZSI) with upstream or
downstream circuit breakers.
•
Setting tsd to the 0 setting turns off zone-
selective interlocking.
selective interlocking.
•
Short-time protection uses true RMS
measurement.
measurement.
•
Short-time pickup and delay can be adjusted
to provide selectivity with upstream or
downstream circuit breakers.
to provide selectivity with upstream or
downstream circuit breakers.
Figure 8:
Short-Time Protection Switches
Table 2:
Micrologic Trip Unit Short-Time Delay Values
Setting
Short-Time Delay
I
2
t off (Isd at 10 Ir) (seconds)
0
0.1
0.2
0.3
0.4
I
2
t on (Isd at 10 Ir) (seconds)
0.1
0.2
0.3
0.4
tsd (min. trip) (milliseconds)
20
80
140
230
350
tsd (max. trip) (milliseconds)
80
140
200
320
500
NOTE: Use I
2
t off with ZSI for proper coordination. Using I
2
t on with ZSI is
not recommended as the delay in the upstream device receiving a restraint
signal could result in the trip unit tripping in a time shorter than the
published trip curve.
signal could result in the trip unit tripping in a time shorter than the
published trip curve.
.4
.5
.6
.7
.8
.9
.95
.98
.98
1
delay
short time
I i
tsd
(s)
on
I
2
t
.
2
.
3
.
4
.
4
.
1
.
2
.
3
.
1
0
off
instantaneous
long time
alarm
Ir
x In
.5
1
2
4
8
12
16
20
20
tr
(s)
@ 6 Ir
24
setting
x Ir
2
2.5
3
4
5
6
8
10
Isd
1.5
x In
3
4
6
8
10
12
15
off
2
06133204
A
B
.4
.5
.6
.7
.8
.9
.95
.98
.98
1
delay
short time
I i
tsd
(s)
on
I
2
t
.
2
.
3
.
4
.
4
.
1
.
2
.
3
.
1
0
off
instantaneous
long time
alarm
Ir
x In
ground fault
B
C
D
E
F
G
H
H
J
Ig
tg
(s)
on
I
2
t
.
2
.
3
.
4
.
4
.
1
.
2
.
3
.
1
0
off
A
.5
1
2
4
8
12
16
20
20
tr
(s)
@ 6 Ir
24
setting
x Ir
2
2.5
3
4
5
6
8
8
10
Isd
1.5
x In
3
4
5
8
10
12
15
off
2
test
06133351
A
B
Micrologic 6.0A Trip Unit
Micrologic 5.0A Trip Unit