9 – 13
Motor protection function
In the circuit breaker position t
sd
=
0.02 sec., a special protection function for electromotive drives is activated. It prevents the short-time
delayed short-circuit tripping from being activated during the switch-on current peak of electric motors. At the same time, a phase failure
protection is activated
and the time constant for the internally calculated reproduction of the temperature rise and cooling
process is switched over from switchgear protection to 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 9-45)
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
ETU748
I
i
> 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
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 - 748
t
g
= 0.1 / 0.2 / 0.3 / 0.4 / 0.5 sec.
ETU776
t
g
= 0.1 - 0.5 sec.
M
Содержание UL 1066
Страница 43: ...6 12 7 Reset reclosing lockout 8 Charge closing spring 9 Switch ON Frame size II Frame size III 9X ...
Страница 56: ...7 5 7 2 Frame size II fused ...
Страница 58: ...7 7 ...
Страница 63: ...7 12 8 27 210 0 8 27 210 0 8 27 210 0 3 75 95 2 ...
Страница 64: ...7 13 ...
Страница 65: ...7 14 7 7 Frame size III fuse carriage ...
Страница 66: ...7 15 ...
Страница 69: ...7 18 7 9 External sensor for neutral conductor WLNCT2 ...
Страница 70: ...7 19 WLNCT3 ...
Страница 85: ...9 5 I tripping Ground fault tripping ...
Страница 231: ...15 12 Pre assembling the locking module Installing 0767 1 2 3 4 6 5 ...
Страница 232: ...15 13 1 Socket head cap screw M5 with washer and nut 7 8 Size 4 5 Nm 45 lb in ...
Страница 271: ...19 10 Function check Then Fit back front panel and side cover on the right if it was removed page 23 4 10 ...
Страница 280: ...21 2 Installing the door sealing frame Not for use with fuse carriages Catalog No Door sealing frame WLDSF 1 2 3 NOTICE ...
Страница 289: ...23 7 23 3 3 Installing arc chutes 1 2 6 5 PH 2 0043 02 3 4 5 6 For frame size III 3 PH 2 ...
Страница 298: ...23 16 6 7 8 9 5 2 1 Size 5 mm ...
Страница 333: ......