Installation guide

Warning
Please Note
The specifications of the product detailed on this
Set-Up Guide may change without notice. RDM
Ltd. shall not be liable for errors or for incidental
or consequential damages, directly and indirectly,
in connection with the furnishing, performance or
misuse of this product or document.
Ensure that all power is
switched off before
installing or maintaining
this product
Revision 2.7 Page 82 of 83
Mercury Plant Controller Installation Guide
Appendix 4 – Supply & Status Input Wiring
Appendix four applies to the current version of the Plant controller hardware.
Method 1. Uses the 24Vac of the transformer supplying the input voltage; which is returned via a switch (or relay)
to the status input signal line. No 0V is required at the status connector.
Method 2. Uses a 0V return (from the status connector) to the status signal input.
Method 3. Uses a 24Vac signal derived from another transformer (supplying an auxiliary piece of kit) to feed the
status input signal line. Note the auxiliary transformer must be referenced to the Plant Controller supply
transformer.
All transformers that have a connection to the Plant Controller must have their primaries connected to the same
phase. Transformer should have fuse fitted in line with 24V input as per diagram.
Note : New versions of hardware have 0V and Earth linked internally via an inductor. Recognisable by Status LED.
See diagram on page 6 for location of status LED
The use of centre tapped to earth transformers is not allowed. This is to prevent damage to the transformer
and/or controller.
With Status LED