GE Industrial Solutions EPM1500 Single Point Submetering System - Manual (Page 24)

2–14 EPM 1500 SUB-METER – INSTRUCTION MANUAL
CHAPTER 2: INSTALLATION
Z Determine which of the transponders should have a telephone
modem, and order a telephone line to terminate at that point.
Do not proceed with the installation until the telephone line is
installed.
Z After the telephone line is installed, install the transponder with
the modem next to the telephone line.
Install all three phases and the neutral to the transponder (see
Installation of Meter and Current Transformers on page 2–9 for
details).
Z If there is more than one transponder, install the other
transponders and the interconnecting RS485 line, if required, which
links all of the transponders
(Go directly to Installation of Meter and Current Transformers on
page 2–9 if there is only one transponder in the system or if each
transponder in the system has a modem and telephone line
connection).
• An RS485 line is a pair of wires, AWG #20 or larger in diameter,
which begins at one transponder where a terminator is placed.
• The RS485 line runs from transponder to transponder ending at
the final transponder, where another terminator is placed.
Note
It is critically important that there should never be three RS485 pairs entering or
leaving a transponder box.
• For the two transponders which have terminators, only one
RS485 pair leaves each box.
• For the other transponders, if there are more than two, exactly
two RS485 lines should leave the box: each line goes to another
transponder in the daisy-chain.
Only one modem should be installed in a data link system. If there
are two or more modems in a data link system, the transponders
will not communicate with each other.
• There may be no more than 32 transponders on a daisy-chain. If
there are more than 32, special care must be taken, which is
beyond the scope of these instructions.
Z If possible, run the RS485 lines in a conduit to protect them from
damage.
Note It is critically important to observe the polarity of the wires. The RS485 data link uses a
black and yellow color code. Match black to black and yellow to yellow; otherwise the
data link will not work.
Z To test the data link, measure the DC voltage across the yellow to
black wire.
This should measure between 0.1 and 0.3 V. If it is negative or
outside of that range, re-check all of the transponder boxes
according to the above specifications.