4 power supply requirements, 1 interface wiring, Ower – Cleveland Motion Controls ULTRA ISC SERIES SLIM CELL TRANSDUCER REV AA User Manual

Page 19: Upply, Equirements

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MAN-70434-0

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ERIES

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RANSDUCER

2.4 P

OWER

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UPPLY

R

EQUIREMENTS

For best performance, a regulated DC power supply that provides a nominal 24 VDC and at least 50 mA per
ISC should be used.

Important: Pay particular attention to the power supply for susceptibility to the effects of conducted and
radiated energy from noise sources. Every effort should be made to provide stable voltage to the amplifier
using correct wiring practices and filters. To protect against circuit damage, include a 0.25 Amp fuse in the
power supply output lead to each amplifier in case of amplifier or power supply malfunction.

The power source for the power supply shall be fused at the proper rating to prevent over current in
the supply leads due to a power supply failure.

Output voltage from the supply should be within +/- 10% of 24 VDC. Component stress due to excessive
supply voltage may damage components and prolonged operation with a higher than necessary voltage will
increase the internal temperature of the circuitry within the ISC. Supply voltages that are excessively low (
either due to a low supply set-point or excessive IR drop of voltage arising by long cable runs ) can result in
“brown-out” of internal regulated supply voltages. This “brown-out” may be evident by the +/- 10V analog
output being clipped at some voltage below 10V. Keep in mind that voltage drops due to long cable runs
may drop the voltage by nearly a half a Volt (250 feet of 24 AWG cable carrying 30 mA will loose 0.4 V).

Although the amplifier provides limited galvanic isolation between the 24 VDC supply circuit and the strain-
gage amplifier circuit, it is only intended as a mechanism to avoid “ground loop” interference. The 24 VDC
supply should always have its output return referenced to P.E. (protective earth), so that uncontrolled
potentials are not imposed between the 24 VDC supply circuit and the load cell case.

For optimum performance, the DC supply voltage should be free from excessive ripple voltage or transient
excursions.

2.4.1 I

NTERFACE WIRING

The load in this connection may be an indicator, recorder, data acquisition device or the analog input
terminals of a control device such as a DC drive or a programmable logic controller. The output signal at this
terminal is undamped and provides a direct response to changes in the transducer (load-cell) load. Note that
the cable’s shield drain wire should be connected at only one end, preferably at the “receiving end” (i.e.
common ground at the PLC Analog Input etc.)

The pair of wires associated with the amplified transducer signal are generally separated out from the 24VDC
supply wires at the point where they get routed toward the tension controller.

For most M12, DC keyed molded cordsets, the wire colors associated with the #1 and #3 pins is BRN and
BLU respectively.

For most M12, DC keyed molded cordsets, the wire colors associated with the #2 and #4 pins are WHT and
BLK respectively. These WHT and BLK wires provide the amplified tension signal transmitted as a +/- 10
VDC Full.Scale. analog signal from an internal op-amp (operational amplifier) buffer stage. The BLK wire
has the signal return and the WHT wire is the amplifier output. Resistive loads drawing up to 5 mA of
current are allowable.

The most common way of reversing the sense of the load cell signal is to invert the mechanical orientation of
the loadcell body itself. If this is impractical, it is possible to interchange the BLK and WHT signal wires, as
the loadcell amplifier and output stage is essentially floating with respect to the 24 VDC supply ground. Note
however that the voltage potential cannot be allowed to float “unbounded”, and that connection to line
potential drive circuits is not permissible (and potentially hazardous).

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