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MODELS 483C30, 483C50, 482M179 AND 483M217 GENERAL OPERATION MANUAL
other grounds in the signal conditioner. This removes one of the grounds in the measurement channel and in most cases
it will eliminate ground loops on that channel.
1-5.
Operation: Standard AC Line
Plug the line cord into a 120V/60 Hz or 230V/50 Hz power source and toggle the "ON/OFF" switch.
CAUTION: Refer to the rear panel for proper input voltage and currents.
1-6.
Maintenance and Repair
It is not recommended that the customer attempt repair of these models in the field. Should trouble occur,
contact the factory for assistance. If the unit becomes dusty and dirty, it may be wiped off with a soft cloth.
2-0.
THEORY OF OPERATION
2-1.
Sensor Excitation
®
ICP
refers to a low output impedance voltage mode sensor combining an integrated circuit and a piezoelectric sensing
element in a single housing to provide a voltage output. This sensor is powered by a +24 VDC power supply having a
constant current, variable from 2 to 20 mA.
Sensor excitation occurs as the constant current of all channels are set. These models allow the constant current to be
adjusted between 2 and 20 mA, when not in isolation mode, to provide the required excitation for most applications.
Special situations, such as driving extra-long cables (more than 1000 ft) with high frequency or fast rise time pulses, may
require increasing the drive current to 12 mA or higher.
When driving fast rise time pulses over long lines, system performances can be optimized by "tuning" the drive current
to the line; i.e. by finding the best current setting for the particular test of physical parameters. To determine the optimal
current setting, experiment with your particular test set up. To insure optimal accuracy in constant-current adjustment,
make sure all channels have sensors or simulated loads, similar to the one provided by the Model 401B04 Sensor
Simulator, consisting of a voltage amplifier similar to those found in ICP® sensors.
2-2.
Input Protection
The input section has protection to limit the amplitude of the incoming signal to within +24 volts to ground. Maximum
allowable input voltage without distortion is ±10 volts, relative to the sensor bias voltage.
®
Figure 2 ICP
Sensor Excitation
4
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