Technical data

37
©1995 Square D—All Rights Reserved
11/98
Overcurrent Protection STR 28D Control Unit
06313078
Trip Curves
Multiple of Current Setting (Ir)
10 20 30 4056789 50
100
60
70 80
90
432
.5 .6 .7 .8 .9
1 1.5
200 300 400 500 600 700 800 900
1000 2000 3000 4000 8000 9000
10000
7000 6000 5000
.01
.1
.02
.03
.04
.05
.06
.07
.08
.09
1
.2
.3
.4
.5
.6
.7
.8
.9
10
2
3
4
5
6
7
8
9
30
40
20
50
60
70
80
90
100
200
300
400
500
600
700
800
900
1000
2000
3000
4000
5000
6000
7000
8000
9000
.01
.1
.02
.03
.04
.05
.06
.07
.08
.09
1
.2
.3
.4
.5
.6
.7
.8
.9
10
2
3
4
5
6
7
8
9
30
40
20
50
60
70
80
90
100
200
300
400
500
600
700
800
900
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
Instantaneous Pickup
I = 1.5–10 x Ir
1.2
10 20 30 4056789 50
100
60
70 80
90
432
.5 .6 .7 .8 .9
1 1.5
200 300 400 500 600 700 800 900
1000 2000 3000 4000 8000 9000
10000
7000 6000 5000
1.2
Time in Seconds
Current Setting:
STR 28D = 0.4–1 x Sensor Rating
STR 28DP = 0.8–1 x Plug Rating