Monroe Electronics Electrostatic Fieldmeter - Static Monitor - model 177A - Manual (Page 9)

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Section 4
INSTALLATION
The Model 177A Multi-Point Fieldmeter and Alarm System, is designed to occupy a 1¾” space in a
standard 19” equipment rack. A minimum of 4” should be left behind the instrument to allow for cable
connections to the back panel.
For use in conjunction with central data collection and/or monitoring, the 177A may be placed at any
convenient, centralized location provided that the distance to any one probe does not exceed 1000
feet. The probes should be placed at any location requiring the monitoring of charge buildup.
An earth ground is necessary for proper operation. The chassis of the instrument may be grounded
through the line cord, but the chassis must be grounded. A three wire grounded line cord is provided
with the unit. The power line connector is located on the rear of the instrument.
NOTE: The wire color code for the line cord provided is:
HIGH SIDE OF LINE — BLACK or BROWN
LOW SIDE OF LINE — WHITE or LIGHT BLUE
SAFETY GROUND — GREEN or GREEN/YELLOW
Probe Inputs:
Four probe-input connectors are located on the instrument back panel. These are 9-pin subminiature
D female receptacles for mating to plugs on either the cables attached directly to the probes or
extension cables or adapter cables used with them. Two captive screws normally furnished with the
plugs may be secured to female thread inserts alongside each receptacle.
At least one probe must be connected for the 177A to operate.
Probes of different full scale sensitivities are available for use with the 177A. Each probe is marked
with a number stamped on the gradient cap to indicate its sensitivity (see Table 1). As a default,
each 177A is shipped with its firmware set to indicate 10KV full-scale. If the installation is using
probes other than 10KV full-scale, the 177A will need to be re-set for a different full-scale value. To
do this, reference the 177A Front Panel Programming Tree shipped with the unit. Place the 177A in
Set-up mode and then navigate to the PT (Probe Type) block as shown in the tree. Change the
probe type value stored to match the full-scale sensitivity of the probe being installed on that
channel. Store the value and then exit the set-up mode.
Outputs:
Two types of outputs are available on the back panel to represent the inputs. Voltage outputs may be
taken at four BNC connectors or 4-20 mA current outputs at screw terminals at JP2. Simultaneous 4-
channel 4-20 mA current output is optional.
The two possible voltage outputs are: [1] ±10 volts, [2] 0 – 5 volts (±2.5 volts full scale).
The positive 4-20mA loop outputs are at terminals 2, 4, 6 and 8 of JP2 for Channels 1-4,
respectively. The returns are at terminals 1, 3, 5 and 7, which are connected to common. The unit
provides a 12V nominal supply which gives a compliance range of 7 volts. An external supply may
be connected which will be used by all 4 channels. The external supply must be less than 25 volts.
Output compliance is external supply minus 5 volts. Note that this supply will be referenced to
chassis and Analog ground. These outputs are in addition to the four voltage outputs. See the
overview of the 4-20mA module in Section 11 on page 30 for more information.