WIRING CONNECTIONS
After the unit has been mechanically mounted, it is ready to be wired. All
wiring connections are made on removable plug-in terminal blocks. There is a
separate terminal block for the bottom board
(TBA)
and optional top board
(TBB)
. All conductors should meet voltage and current ratings for each terminal.
Also cabling should conform to appropriate standards of good installation, local
codes and regulations. It is recommended that power supplied to the unit be
protected by a fuse or circuit breaker. When wiring the unit, remove the terminal
block and use the numbers on the label to identify the position number with the
proper function. Strip the wire, leaving approximately 1/4" bare wire exposed
(stranded wires should be tinned with solder)
. Insert the wire into the terminal
and tighten down the screw until the wire is clamped tightly. Each terminal can
accept up to one 14-gage, two 18-gage or four 20-gage wire
(s)
. After the terminal
block is wired, install it into the proper location on the PC board. Wire each
terminal block in this manner.
POWER WIRING
Primary AC power is connected to TBA #1 and 2
(marked VAC 50/60 Hz,
located on the left hand side of the bottom terminal block, as you face the rear of
the meter)
. To reduce the chance of noise spikes entering the AC line and
affecting the indicator, the AC power should be relatively
“clean”
and within the
spe/-10% variation limit. Drawing power from heavily loaded circuits or
circuits which also power loads that cycle on and off,
(contactors, relays, motors,
machinery, etc.)
should be avoided.
CAUTION: Disconnect power to all unit terminals before removing
terminal blocks. This includes deenergizing the current transformer
primary circuit.
SIGNAL WIRING
AC signal wires are connected to TBA #5 and 6. If AC signal current greater
than 5 amps AC is going to be applied, the appropriate size slow blow fuse should
be installed.
CAUTION: The IMH is intended to be used with a 5 amp AC
current transformer. Use without a current transformer will place
the meter’s input and output terminals at the measured circuit’s
potential.
CAUTION: It is recommended that the current transformer be
internally protected or that a voltage clamping circuit be provided,
preventing dangerous high voltage across the CT secondary
windings in case of accidental opening of the secondary output
leads when the primary is energized. In order to prevent risk of
electric shock ensure CT is installed according to local NEC
regulations for installation of current instrument transformers.
USER INPUT WIRING
User inputs (PGM.DIS., E1-CON, and optional E2-CON) are digital inputs
that are active when connected to TBA #5 Common. Any form of mechanical
switch, sinking collector logic with less than 0.7 V saturation may be used. The
use of shielded cable is recommended. Follow the EMC Installation Guidelines
for shield connection.
OUTPUT WIRING
RELAY CONNECTIONS
To prolong contact life and suppress electrical noise interference due to the
switching of inductive loads, it is good installation practice to install a snubber
across the contactor. Follow the manufacturer’s instructions for installation.
Note: Snubber leakage current can cause some electro-mechanical devices to be
held ON.
-30-
Basic Connection