Danfoss VLT CDS 303 - Page 13

(see Figure 2.7). Connecting inputs increases the probability
of a fault in the unsafe direction. A fault in one frequency
converter can result in all frequency converters becoming
enabled. The probability of a fault for T37 is so low, that
the resulting probability still meets the requirements for
SIL2.
130BC972.10
12
37
1
3
4
2
Figure 2.4 STO Example
1 Frequency converter
2 [Reset] key
3 Safety relay
4 Emergency stop
Table 2.3 Legend to Figure 2.4
130BC973.10
18
37
4
1
2
12
3
Figure 2.5 SS1 Example
1 Frequency converter
2 [Reset] key
3 Safety relay
4 Emergency stop
Table 2.4 Legend to Figure 2.5
130BC974.10
12
37
K 1
K 1
K 1
4
1
3
2
Figure 2.6 STO Category 4 Example
1 Frequency converter
2 [Reset] key
3 Safety relay
4 Emergency stop
Table 2.5 Legend to Figure 2.6
Safety Instructions and Gen... Operating Instructions
MG34M422 Danfoss A/S © Rev. 2013-07-03 All rights reserved. 11
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