Siemens ET 200M, Manual, Page: 239 / 284

16-Channel, 24-150 VDC/120-230 VAC Relay Output MTA
Marshalled Termination Assemblies for ET200M Remote I/O Modules
A5E00482820-12 239
18.5 Maintenance
See Section 3, Maintenance , before performing any maintenance and observe all
warnings
Under normal operation, the
A/B Power LEDs and the Module 1/2 Fuse LEDs are
on. If all are off, check the power supply to MTA. If the A/B Power LEDs are off,
check the power supply to the MTA. If the Module 1/2 Fuse LEDs are off, check
the channel fuse and replace as necessary.
The relays are socketed to allow replacement in the field. A relay may be replaced
in non hazardous locations with power applied to the MTA (see warning below).
Only the channel associated with that relay will be affected. Some relay positions
have near-by components that prevent finger access. The use of long-nose pliers
will be needed for those locations. See figure 15-1.
Replacement of a relay can be facilitated by removing the cable connectors and
frame. Reference figure 1-2 for information on the frame. It may also be helpful to
unplug the field connector adjacent to the relay that you are replacing.
Note
Multiple simultaneous channel short circuits or overloads may cause the module
power fuse (on the MTA) to open. Repair the channels short circuits and
overloads as soon as possible.
! Warning
Electrical shock hazard
•
An electrical shock hazard exists for Relay Output MTAs only when connected
to loads with voltage > 30V rms and 42.4V peak or 60V dc
•
Remove power from all wires and terminals before working on equipment.
•
For voltages greater than 150 VDC, all channels must be of the same voltage.
For AC voltages all channels must be the same phase for the channels in one
group. There can be different phases between groups.