ABB CIRCUIT SHIELD 49/50/51 Manual de instruções - Página 8
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IB 7.2.1.7-4
Page 8
Fivure
-4
Type
49
Allowable Time Between Overloads
for
a
2
Minute Curve
Trip Times in Percent of Times
from Time-Current Curves
0%.._~~~~~
.....
----------~
0
2.4
4.8
Minutes Between Successive 0Verl0&d•
Motor Overcurrent Relay
Figure
6
Example
Type
49/50/51
Composite Motor Protection
Overload Unit Set at
1.2
times full load amps.
Locked Rotor Unit set at
5
second curve.
Instantaneous Unit Set at 7.2 times full load amps
1000
1000
100
.a
8
Locked Rotor
•
10
Ill
c:
...
I
1
...
f4
Locked Rotor Unit '511
.l
.01
0
l
:z
l
4
5
'
7
•
!I
10
Current in Multiple• of full Load Aapere1
Figure
5
Example
Type 49
Typical Operation of Thermal Memory Unit
2 Minute Time Dial
Motor current
IA
in \
Of
,.,,
Relay Tap Setting
//)()
Contents
of Thermal
Me1110ry
~
in \ of Total
0
I
I
1
"
I
I
/
RELAY TRIPS
!
I
r-
·-·---1-
(
___
2
.3
4
.$
7
8
'f
ID
II
12
Time in Minutes