20
3.2.5 SAFETY OUTPUT CONNECTION
Three normally
-
open safety outputs are provided. In low to medium risk applications
the machine is normally provided with a single MPCE.
In such cases both safety outputs should be connected in series with the MPCE coil as
shown in Figure 21. If the machine is fitted with two MPCEs, one safety output should
be connected in series with each MPCE coil as shown in Figure 22.
To protect the contacts of the safety output relays from the effects of switching
inductive loads, it is recommended that arc suppressors should be fitted in parallel
with the MPCE coils as shown Figures 21 and 22. Arc suppressors must not be fitted
across the safety relay contacts.
To protect against the possibility of both safety outputs welding in, due to an
overcurrent fault in the machine circuit, 2A fuses should be fitted in series with the
MPCE coils as shown in Figure 21 and 22. This limits the current through the safety
output contacts to well below that which could cause the contacts to weld.
Figure 21
–
Safety Output Connection (single MPCE)
Figure 22
–
Safety Output Connection (Two MPCEs)
