Datasheet

SFN4D
7
ds_61408_0000_en_sfn4d: 141106D
Failure modes, application examples
1. Self-holding circuit, three safety circuits
One contact welded, e.g. NO 9-10 of K1.
Condition of contacts at deenergized coil
One contact welded, e.g. NO 12-11 of K2.
Condition of contacts at deenergized coil
2.1. Four safety circuits
(see wiring example, p. 8)
One contact welded, e.g. NO 9-10 of K1.
Condition of contacts at deenergized coil
One contact welded, e.g. NO 12-11 of K2.
Condition of contacts at deenergized coil
2.2. Two safety circuits
(see wiring example, p. 8)
Both contacts of one path are welded,
e.g. NO 7-8 and NO 14-13.
A safety circuit needs two paths in this
failure mode. The contacts 9-10, 12-11,
and 14-13 of K1 interrupt the load.
Condition of contacts at deenergized coil
Both contacts of one path are welded,
e.g. NO 9-10 and NO 12-11.
A safety circuit needs two paths in this
failure mode. The contacts 7-8, 12-11,
and 14-13 of K1 interrupt the load.
Condition of contacts at deenergized coil
1) Feedback loop, 2) Self-holding circuit, 3) Safety circuit, 4) Auxilliary contacts
5
6
7
8
9
10 11
12
13
14
15
16
6
5
13
14
11
12
9
10
7
8
16
15
K1
K2
1) 2) 2) 3) 3) 3) 4)
5
6
7
8
9
10 11
12
13
14
15
16
6
5
13
14
11
12
9
10
7
8
16
15
K1
K2
5
6
7
8
9
10 11
12
13
14
15
16
6
5
13
14
11
12
9
10
7
8
16
15
K1
K2
5
6
7
8
9
10 11
12
13
14
15
16
6
5
13
14
11
12
9
10
7
8
16
15
K1
K2
1) 3) 3) 3) 3) 4)
6
5
13
14
11
12
9
10
7
8
16
15
5
6
7
8
9
10 11
12
13
14
15
16
K1
K2
5
6
7
8
9
10 11
12
13
14
15
16
6
5
13
14
11
12
9
10
7
8
16
15
K1
K2
5
6
7
8
9
10 11
12
13
14
15
16
6
5
13
14
11
12
9
10
7
8
16
15
{
{
1) 3) 3) 4)
K1
K2
5
6
7
8
9
10 11
12
13
14
15
16
6
5
13
14
11
12
9
10
7
8
16
15
K1
K2
5
6
7
8
9
10 11
12
13
14
15
16
6
5
13
14
11
12
9
10
7
8
16
15
K1
K2