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DewPro MMY245
displayed using the procedures for
titled 2.5.5 Special Output and Input Functions.
2.5.6.3.1
Current Inputs
When reading a 4-20 mA signal from an external device, use a 249 Ω resistor across the wires for a 1-5
VDC input.
Example Conditions:
1. Input device is a MMY30 with –90 to +10 as the 4-20mA span settings.
2. Sense resistor is 249 Ohms
3. Output voltage of MMY245 must span 1 to 5 volts given the 4-20mA span of the MMY30.
Required Settings:
V5 H4
-90
1.
=
V5 H5
10
2.
=
V5 H6
1.00
V (4mA * 249 Ohms = 0.996V ≈ 1.00V)
3.
=
V5 H7
4.98
4.
=
V (20mA * 249Ohms = 4.98V)
V5 H8
1.00
5.
=
V5 H9
5.00
6.
=
Therefore as the 4-20mA signal is sensed by the 249 Ohm resistor as a voltage between 1.00 and 4.98 volts,
the display in matrix location
between 1.00 and 5.00 volts to match.
2.5.6.4 Output connections
The DewPro MMY245 can provide 0-5 VDC outputs for recording or logging the readings using the
power and output cable P/N 63002013. This cable will allow connection of the DC power using the Green
(+ for output 1) and Black (-) or the White (+ for output 2) and Black (-) wires per the drawing MSY35C in
the appendix of this manual. The output impedance is 100 Ω. This must be connected to a recorder or
logger with an input resistance of at least 20 KΩ to provide 0.5% accuracy. A higher input impedance is
recommended for better signal accuracy. These outputs are scaled and referenced to specific units of
V1 H0
measure using
, through
section 2.5.5 above titled 2.5.5 Special Output and Input Functions.
3 Troubleshooting
Field maintenance consists of keeping the instrument clean replacing the batteries when the unit indicates
V8 H5
they are low (see
position over night will provide an indication of how well the desiccant can dry down the sensor. If this
reading is above –30°C dew point, return the unit to the factory for desiccant replacement and service.
3.1 General Troubleshooting Practice
Troubleshooting will be helpful in case the instrument does not perform and has an error indication on the
display. This troubleshooting guide is limited to the function of the unit and is not intended to address
questionable readings where there is no error code present. Suspected errors in readings should be dealt
with first by insuring all connections are leak free and that the unit of measure is correctly set. The pressure
compensation mode should be verified that it is set correctly for the application. After these items are
verified to be correct, and if the unit still produces questionable readings, contact the General Eastern
factory field service department by calling 800-33HUMID (334-8643) for further assistance.
General Troubleshooting Guide
GE General Eastern
V5 H4
V5 H5
,
V4 H0
will show a linear value between –90 and +10 with a voltage output
V2 H7
for output 1, and
). In addition, monitoring the reading after leaving the handle in the bypass
Installation and Operation Manual
V5 H6
V5 H7.
,
, and
V5 H0
through
See the section 2.5.5 above
V5 H4
for output 2. See the
17
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Table of Contents
Troubleshooting
