Danfoss VLT Safety Option MCB 150 Installation Manual page 50

Installation Guide | VLT® Safety Option MCB 150/151
A
b
24 V DC
c
0 V
A Safety PLC
C GND
Illustration 34: Connecting a Digital Output Module, for Example Safety PLC
MCB15x
A
10
1
3
Illustration 35: Connecting a Sensor, for Example 1-channel Emergency Stop Mushroom Pushbutton or Limit Switch
All equipment used must be suitable for the selected category/PL or SIL.
Use of a 1-channel E-stop switch provides no input redundancy, and no ability for the safety option to monitor for input short
circuits. One-channel E-stop switches used with a safety option are suitable only for Category 2 applications, per EN ISO
13849-1 PL c or SIL1.
When a 1-channel E-stop is used, guard against failure modes that can result in an unsafe condition. An example of an unsafe condition
could be the failure of the contact to a short circuit condition. A switch with positive opening operation should be used to reduce the
possibility of a failure of the switch to open. A short-circuit failure results in loss of switching function. This failure can occur from a
short across the switch contacts, a short across the wires connected to the switch between the switch and the safety option, or a short
to a secondary source of power. To reduce these risks, physically separate the wires from each other and from other sources of power
(for example, in separate wire ways or conduit). According to the definition of European standard EN ISO 13849-1, a 1-channel E-stop
could be used in applications where PL c or less (b or a) has been determined via a risk-assessment procedure.
50 | Danfoss A/S © 2018.09
D
MCB15x
12
1
3
12 37
11 20
B
12
12 37
11
20
B Safety output
D Drive
N O T I C E
N O T I C E
Installation
AQ279747441421en-000101 / 130R0292