EMC Installation Guidelines
Although this unit is designed with a high degree of immunity
to ElectroMagnetic Interference (EMI), proper installation and
wiring methods must be followed to ensure compatibility in each
application. The type of electrical noise, source or coupling
method into the unit may be different for various installations.
Cable length, routing and shield termination are very important
and can mean the difference between a successful or a trouble-
some installation. Listed below are some EMC guidelines for
successful installation in an industrial environment.
1. The unit should be mounted in a metal enclosure, which is
properly connected to protective earth.
2. Use shielded (screened) cables for all Signal and Control inputs.
The shield (screen) pigtail connection should be made as short
as possible. The connection point for the shield depends
somewhat upon the application. Listed below are the
recommended methods of connecting the shield, in order of their
effectiveness.
a. Connect the shield only at the panel where the unit is mounted to
earth ground (protective earth).
b. Connect the shield to earth ground at both ends of the cable,
usually when the noise source frequency is above 1 MHz.
c. Connect the shield to common of the unit and leave the other
end of the shield unconnected and insulated from earth ground.
3. Never run Signal or Control cables in the same conduit or
raceway with AC power lines, conductors feeding motors,
solenoids, SCR controls, and heaters, etc. The cables should be
run in metal conduit that is properly grounded. This is especially
useful in applications where cable runs are long and portable
two-way radios are used in close proximity or if the installation is
near a commercial radio transmitter.
4. Signal or Control cables within an enclosure should be routed as
far away as possible from contactors, control relays,
transformers, and other noisy components.
5. In extremely high EMI environments, the use of external EMI
suppression devices, such as ferrite suppression cores, is
effective. Install them on Signal and Control cables as close to
the unit as possible. Loop the cable through the core several
times or use multiple cores on each cable for additional
protection. Install line filters on the power input cable to the unit
to suppress power line interference. Install them near the power
entry point of the enclosure.
The following EMI suppression devices (or equivalent) are
recommended:
Ferrite Suppression Cores for signal and control cables:
Fair-Rite # 0443167251 (RLC #FCOR0000)
TDK # ZCAT3035-1330A
Steward #28B2029-0A0
Line Filters for input power cables:
Schaffner # FN610-1/07 (RLC #LFIL0000)
Schaffner # FN670-1.8/07
Corcom #1VR3
Note:Reference manufacturer’s instructions
when installing a line filter.
6. Long cable runs are more susceptible to EMI pickup than short
cable runs. Therefore, keep cable runs as short as possible.
5.0 WIRING CONNECTIONS
The electrical connections are made via screw-clamp terminals
located on the back of the unit. When wiring the unit, use the
label to identify the wire position with the proper function. 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 recom-
mended that power supplied to the unit be protected by a fuse
or circuit breaker. Strip the wire, leaving approximately 1/4"
bare wire exposed (stranded wires should be tinned with
solder). Insert the wire into the screw-clamp terminal and
tighten the screw until the wire is clamped tightly. Each terminal
can accept up to two #14 AWG wires.
6.0 DECIMAL POINT SELECTION
The DTM Digital Tension Meter can be set-up to read in 10ths,
100ths, or 1000ths. The decimal point position is DIP switch
selectable for one of three locations. If all the DIP switches are
set to the “OFF” position, then NO decimal point will appear in
the display. The DIP switches are located at the rear of the unit.
7.0 DTM SIGNAL INPUT
The SCALE DIP switch (S1) and the Scaling Potentiometer
are used to scale the display to the desired maximum tension
indication. The Scale switch should be left in the “ON” position
for use as a tension meter.
When the power supply is floating (unreferenced) to the desired
measurement points, the (-) signal input and the power supply
common should be connected. If the power supply is not
floating (referenced), the common mode voltage between the
(-) signal input and power supply common terminal must not be
greater than 1.0 V peak. A common mode voltage higher than
1.0 V peak will result in a measurement error.
The Calibration Potentiometer has been set at the factory and
should not be adjusted unless the unit is being re-calibrated
with an accurate current source.
CAUTION: The Maximum Current of 10 mA must
not be exceeded or the unit may be damaged.
(See Specifications).
Figure 3 –DTM Signal Input
Figure 2 –DTM Installation Dimensions and Panel Cutout
