
9 – 12
Motor protection function
When the short-time delay is set to 20ms (t
sd
=
0.02 sec.), a special motor protective function is enabled which prevents short-time
tripping during the turn-on inrush for motors. At the same time, a phase loss sensing function is enabled
constant used for long-time protection is changed from one suitable for bus protection to one suitable for motor protection.
Instantaneous short-circuit tripping – I-tripping
If the current setting I
i
is exceeded, the circuit breaker is tripped instantaneously.
Ground-fault tripping – G-tripping
If the trip unit is equipped with a ground-fault protection module, loads can be protected against impermissibly high ground-fault currents.
Trip units ETU745 - 776 can be equipped with it optionally.
Ground-fault protection modules (page 9-44)
The response value I
g
, together with the setting for the delay time t
g
, determines the shutdown of ground-fault currents.
If the zone selective interlocking (ZSI)
is used and the ZSI module is set to "S" or "S+G" the adjusted delay time t
g
is auto-
matically set to 100 ms provided that in the event of ground-fault the circuit breaker does not receive a blocking signal from a downstream
circuit breaker. In this case regardless of the adjusted t
g
value the circuit breaker will trip after 100 ms.
If a blocking signal exists the adjusted delay time t
g
is valid. For safety reasons after 3 s the blocking signal is terminated. Some trip units
can be switched over to an I
2
t-characteristic.
Setting values for I
i
ETU745
OFF: I
i
= I
CW
I
i
= (1.5 / 2.2 / 3 / 4 / 6 / 8 / 10 / 12 × I
n
MAX = 0.8 x I
CW
ETU776
I
i
= 1.5 x I
n
- 0.8 x I
cs
; OFF
:
I
i
= I
CW
Setting values for I
g
Frame size
I & II
III
A
100 A
400 A
B
300 A
600 A
C
600 A
800 A
D
900 A
1000 A
E
1200 A
1200 A
Setting values for t
g
ETU745
t
g
= 0.1 / 0.2 / 0.3 / 0.4 / 0.5 sec.
ETU776
t
g
= 0.1 - 2.0 sec.
M
Summary of Contents for UL 489
Page 36: ...5 21 Frame size II 3000 A Frame size III 1 Holes 14 mm 0720 1 0721_nu ...
Page 63: ...7 2 Horizontal connectors 0733_nu top view ...
Page 64: ...7 3 Rear vertical connectors 0734_nu top view rear view ...
Page 65: ...7 4 Front connectors 0736_nu front view top view ...
Page 66: ...7 5 Front connectors and pressure wire terminals 0737_nu top view front view ...
Page 67: ...7 6 7 2 Frame size II fixed mounted version 0494 3_nu ...
Page 68: ...7 7 Class C always 0494 5_nu top view rear view ...
Page 69: ...7 8 2500 0738_nu LH side view front view ...
Page 71: ...7 10 7 4 Frame size III fixed mounted version 0495 1_nu LH side view ...
Page 72: ...7 11 0495 2_nu top view top view ...
Page 73: ...7 12 0495 3_nu top view rear view ...
Page 75: ...7 14 7 5 Door cut outs fixed mounted circuit breaker Frame size I 0735_nu ...
Page 76: ...7 15 Frame size II III 0496_nu ...
Page 77: ...7 16 7 6 Frame size I draw out version 0745_nu ...
Page 78: ...7 17 0746_nu rear view top view ...
Page 79: ...7 18 0747_nu bottom view ...
Page 80: ...7 19 0748_nu ...
Page 81: ...7 20 0749_nu ...
Page 82: ...7 21 7 7 Frame size II draw out version 0490 1_ul ...
Page 86: ...7 25 7 8 Frame size III draw out version ...
Page 87: ...7 26 ...
Page 88: ...7 27 ...
Page 89: ...7 28 7 9 Door cut outs for draw out circuit breakers Frame size I 0750_nu ...
Page 91: ...7 30 7 11 External sensor for neutral conductor WLNCT2 ...
Page 92: ...7 31 WLNCT3 ...
Page 107: ...9 5 I tripping Ground fault tripping ...
Page 351: ......