General Eastern E4-1111H-GE Operating Manual
E4-1111H-GE
DEW POINT MONITOR
Operator’s Manual
The information in this manual is believed to be reliable.
However, General Eastern makes no warranty, expressed or implied, as to its accuracy and assumes no
liability arising out of its use by others. We reserve the
right to change this manual without prior notice.
Document No. A40232856/A00 ECO #5521
October 31, 2001 Printed in U.S.A.
Copyright
2001 General Eastern Instruments
The Humidity Experts
General Eastern Instruments
20 Commerce Way, Woburn, MA 01801-1057
Tel: (781) 938-7070 Fax: (781) 938-1071
Safety:
This manual as well as safety labels posted on the instrument use the
following safety alerts to draw your attention to special safety instructions
that should be followed.
CAUTION
CAUTION: Hazards or unsafe practices could result in electrical shock, minor
injury, or product damage.
WARNING
WARNING: Refer to accompanying document for additional information.
ALERT:
ALERT
Earth ground connection; removal could result in electrical shock,
minor injury, or product malfunction.
CONTENTS
CHAPTER 1 — INTRODUCTION
About General Eastern - - - - - - - - - - - - - - - - - - - - - - 1
Overview of the E4-1111H-GE - - - - - - - - - - - - - - - - - - 1
The humidity sensor - - - - - - - - - - - - - - - - - - - - - - - 3
Theory of operation - - - - - - - - - - - - - - - - - - - - - - - - 3
CHAPTER 2 — INSTALLATION
Mounting - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 7
Input power - - - - - - - - - - - - - - - - - - - - - - - - - - - - 8
Wiring the outputs - - - - - - - - - - - - - - - - - - - - - - - - 9
Sensor information - - - - - - - - - - - - - - - - - - - - - - - 12
Sensor replacement - - - - - - - - - - - - - - - - - - - - - - - 13
CHAPTER 3 — OPERATION
General information - - - - - - - - - - - - - - - - - - - - - - - 15
Control switches - - - - - - - - - - - - - - - - - - - - - - - - 15
RS-232C data outputs - - - - - - - - - - - - - - - - - - - - - - 17
Helpful hints for operating the unit - - - - - - - - - - - - - - - 17
The PACER Cycle - - - - - - - - - - - - - - - - - - - - - - - - 21
CHAPTER 4 — PROGRAMMING
General information - - - - - - - - - - - - - - - - - - - - - - - 23
RS-232C programming - - - - - - - - - - - - - - - - - - - - - 23
CHAPTER 5 — SERVICE
Minor maintenance of sensor optics - - - - - - - - - - - - - - - 31
Field replacement of sensor mirror - - - - - - - - - - - - - - - 32
Test and calibration - - - - - - - - - - - - - - - - - - - - - - - 35
Troubleshooting - - - - - - - - - - - - - - - - - - - - - - - - - 35
- - - - - - - - - - - - - - - - - - - - - - - 31
- - - - - - - - - - - - - - - - - - - - 1
- - - - - - - - - - - - - - - - - - - - 7
- - - - - - - - - - - - - - - - - - - - - 15
- - - - - - - - - - - - - - - - - - - 23
APPENDIX A — SPECIFICATIONS
APPENDIX B — WARRANTY AND RETURN PROCEDURE
- - - - - - - - - - - - - - - - - - 39
- - - - - - 41
APPENDIX C — HUMIDITY EQUATIONS AND CONVERSION CHART
APPENDIX D — CONFIGURING THE RS-232 INTERFACE
APPENDIX E — GLOSSARY
- - - - - - - - - - - - - - - - - - - - - 53
- - - - - - 49
45
FIGURES
Figure 1 Dimensions
Figure 2 The chilled-mirror hygrometer
Figure 3 Front view
Figure 4 Side view
Figure 5 Rear view
Figure 6 PC Board
Figure 7 Wiring and sensor replacement
Figure 8 DIP Switches
Figure 9 The PACER cycle
Figure 10 Results of the PACER cycle
Figure 11 Scaling parameters
Figure 12 Balance adjustment screw locations
Figure 13 Using a Resistance Decade Box
- - - - - - - - - - - - - - - - - - - - - - - 3
- - - - - - - - - - - - - - 4
- - - - - - - - - - - - - - - - - - - - - - - 7
- - - - - - - - - - - - - - - - - - - - - - - - 8
- - - - - - - - - - - - - - - - - - - - - - - - 9
- - - - - - - - - - - - - - - - - - - - - - - 10
- - - - - - - - - - - - - 11
- - - - - - - - - - - - - - - - - - - - - 16
- - - - - - - - - - - - - - - - - - - 21
- - - - - - - - - - - - - - - 22
- - - - - - - - - - - - - - - - - - - 25
- - - - - - - - - - - - - 37
- - - - - - - - - - - 32
Chapter 1 — Introduction
About General Eastern
General Eastern is devoted solely to the design and manufacturing
of accurate, reliable and rugged humidity measuring equipment.
We specialize in providing solutions for applications where
humidity measurements are critical.
There are many ways to make humidity measurements, and no one
humidity sensor meets all requirements for all applications. Our
variety of sensor types — including chilled mirror, lithium chloride,
resistance polymer, and wet bulb — can precisely determine dew
point, parts per million by volume, percent relative humidity, and
other parameters.
In keeping with General Eastern’s philosophy of providing the best
solutions to humidity measurement problems, we offer the
following products and services:
• high quality state-of-the-art instrumentation to assure excellent performance
• a broad range of humidity instruments capable of covering virtually any humidity measurement application
• full applications assistance to help you choose the sensor that
is best for your needs
• full and superior service, should it ever be needed
If you have questions about a particular measurement problem, we
invite you to call and discuss your application with one of our engineers. Call 800-225-3208 (if you’re calling from Massachusetts or
outside the United States, call 781-938-7070). Our fax number is
781-938-1071.
Overview of the E4-1111H-GE
The General Eastern E4-1111H is a multi-purpose chilled-mirror
hygrometer, suitable for use in a variety of applications. The unit
measures dew/frost point from –25°C to +65°C (–13°F to +149°F).
Chapter 1 — Introduction
1
The E4-1111H is designed for wall or surface mounting. It is
housed in a gasketed NEMA-4 aluminum enclosure, suitable for
industrial environments.
A 4–20mA analog output is provided as well as an RS-232C
communications port.
A red indicator light shows when
indicator light shows that the unit’s
tion (see “The PACER Cycle” beginning on page 21).
The monitor utilizes advanced microprocessor control and includes
General Eastern’s patented Programmable Automatic Contaminant
Error Reduction (PACER) system to insure accuracy.
Detailed specifications are given in Appendix A, beginning on
page 39.
POWER
BALANCE
is applied and a green
function is in opera-
System
Components
Physical
description
The complete system is packaged with the following items:
• The electronic monitor with integrated dew point sensor and
filter
• Operator’s manual
• Certification that the unit is traceable to the National Institute
of Standards and Technology
The E4-1111H is designed for surface mounting on a vertical wall
or panel. The unit’s dimensions are shown in Figure 1 in inches
(cm).
2
E4-1111H-GE Operator’s Manual
)
n
Ø 0.50 (12.7
4 plcs
3
Removable filter
17.36 (44.1)
2.75
(70)
8 (20.3)
10 (254)
10.5 (267)
The humidity sensor
The monitor is configured with a General Eastern 1111H
single-stage chilled-mirror dew point sensor. The sensor provides
data to the electronics unit that calculates humidity.
18.4 (468)
dimensions in
inches (mm)
4.25 (108)
Sensor Probe
1/2" Conduit fittings
Figure 1 — Dimensions
9.2 (237)
Figure 1 — Dimensions
1.5 (39)
dimensions i
inches (mm)
Theory of operation
What is Optical
Condensation
Hygrometry?
Chapter 1 — Introduction
Optical condensation hygrometry is a precise technique for determining the water vapor content in gases by directly measuring dew
point or frost temperatures. Using this technique, a metallic mirror
is cooled until it reaches a temperature at which a thin layer of
condensation begins to form on it. The dew layer is detected optically, and the mirror is held at that temperature. The mirror
temperature, measured with a platinum resistance thermometer, is
r
an accurate indicator of the dew or frost point. Because these
hygrometers are so accurate, they are widely used as a standard in
many of the world’s metrology laboratories.
How do General
Eastern
hygrometers
function?
Figure 2 illustrates how General Eastern hygrometers detect and
measure dew point. The condensate mirror is illuminated with a
high-intensity, solid state, light emitting diode (LED). A photodetector monitors the LED light reflected from the mirror. The photodetector is fully illuminated when the mirror is clear of dew, and it
receives less light as dew forms. A separate LED and photodetector
pair are used as a known reference to compensate for any thermally
induced changes in the optical components. The photodetectors
are arranged in an electrical bridge circuit, the output current of
which is proportional to the light reflected from the mirror. The
bridge output controls the electrical current to the thermoelectric
cooler.
Figure 2 — The chilled-mirror hygromete
A large bridge current develops when the mirror is dry, causing the
mirror to cool toward the dew point. As dew begins to form on the
mirror, less light is reflected, and the bridge output decreases. This,
in turn, causes a decrease in cooling current. A rate feedback loop
4
E4-1111H-GE Operator’s Manual
5
within the amplifier ensures critical response, causing the mirror to
stabilize quickly at a temperature that maintains a thin dew or frost
layer on the mirror surface. A precision thermometer element
embedded within the mirror directly monitors this dew point
temperature.
Using General
Eastern
Hygrometers as a
standard for
calibration
An optical condensation hygrometer such as the E4-1111H can be
sent to the National Institute of Standards and Technology (NIST)
in Gaithersburg, Maryland for calibration against the NIST standard. A calibrated instrument can then be used as a transfer standard in local laboratories to calibrate lower echelon instruments.
Hygrometers used as calibration standards must have the following
characteristics:
• The mirror thermometer must have suitable long-term accuracy (such as that obtained with a platinum resistance thermometer).
• A means must be provided for viewing the dew or frost formation on the mirror.
Chapter 1 — Introduction
6
E4-1111H-GE Operator’s Manual
Mounting
)
Chapter 2 — Installation
Mount the E4-1111H on a vertical surface using the four mounting
holes at the corners of the unit. Provide adequate space below the
unit for cabling, and to the left of the unit to allow the door to open
fully. The sensor module protrudes from the rear of the unit into
the measurement space. Mounting dimensions are shown in
Figures 3, 4 and 5.
Ø 0.50 (12.7
4 plcs
17.36 (44.1)
18.4 (468)
dimensions in
inches (mm)
Figure 3 — Front view
8 (20.3)
10 (254)
10.5 (267)
2.75
(70)
Chapter 2 — Installation
7
n
Removable filter
Sensor Probe
1.5 (39)
Input power
1/2" Conduit fittings
dimensions i
inches (mm)
4.25 (108)
9.2 (237)
Figure 4 — Side view
The E4-1111H is available in versions wired for 115, 230, and 100
VAC. The 230 VAC version is double-fused.
The unit’s voltage and frequency rating and tolerances, as well as
fusing data, are listed inside the unit.
Input power wiring enters through the bottom edge of the unit and
connects to the right-hand terminal block as shown in Figure 7.
8
E4-1111H-GE Operator’s Manual
n
Ø
0.50 (12.7)
4 plcs
5.63
(143)
I+
Wiring the outputs
The E4-1111H’s output terminals are located inside the unit’s front
door. Cabling is brought in through the bottom edge of the unit
and connected to terminal blocks as shown in Figure 7.
Analog humidity
output
The humidity output provides a 4–20mA analog signal (500 Ohms
maximum load). Connect to the terminals labelled
the left-hand terminal block.
4 (10.15)
8 (20.3)
4 (10.15)
11.73
(298)
17.36
(441)
dimensions i
inches (mm)
Figure 5 — Rear view
and
RTN
on
Chapter 2 — Installation
9
d
The humidity units and scaling may be set using the RS-232C port.
See “Chapter 4 — Programming” beginning on page 23 for details.
.
DIP switches
RS-232 Connector
Switch 1
Right Side (closed)Left Side (open)
Switch 8
PC Boar
Figure 6 — PC Board
Service output
10
The
SRVC
output provides a TTL-compatible signal that indicates
that the mirror needs cleaning (see page 31).
Connect to the terminals labelled
SRVC
and
Figure 7.
E4-1111H-GE Operator’s Manual
RTN
as shown in
RS-232C
connector
The RS-232C connector is located at the bottom edge of the PC
board (see Figure 6). It provides RS-232C digital communications
between the unit and an RS-232C terminal or a PC running in
terminal emulation mode.
Sensor mounting
plate
Sensor cable
connection
Wing nuts (4 plcs)
SRVC
RTN
L (line)
I+
Ground
N (neutral)
AC power
Chapter 2 — Installation
Outputs
Figure 7 — Wiring and sensor replacement
The connector is a standard 25-pin D connector. For connection to
another RS-232C device, the cable is wired as shown below. Pin
connections are given for both 25-pin and 9-pin devices.
11
E4-1111H
25-pin device 9-pin device
232
323
775
The baud rate of the data is 1200. The format of the data is 8 data
bits, 1 stop bit, and no parity.
The unit can communicate with a handheld RS-232C terminal or a
personal computer running in terminal emulation mode. See
Appendix D for a BASIC computer program that can be used for
simple RS-232C communications between the unit and your PC.
Handshaking.
to
NO HANDSHAKE
In order to enable handshaking, the RS-232C menu must be
accessed through the RS-232C port. See “Handshake control” on
page 28 for details. To implement handshake control using
Clear-To-Send and Ready-To-Send, use pins 4 and 5. Applying 8
volts (
transmit.
3) to Pin 5 of the RS-232C connector allows the unit to
±
The default handshaking protocol for the unit is set
.
Sensor information
Filter
Requirements
Flow Rate
12
The E4-1111H is equipped with a submicron Teflon filter to avoid
particulate contamination and to protect the sensor from the presence of liquid water. In many applications, the filter requires periodic inspection and replacement. Typical applications might
require replacement twice a year.
It is important to have adequate flow through the sensor. Too little
flow can slow the response (particularly at very low frost points).
E4-1111H-GE Operator’s Manual
Too much flow can cause instability of the control system at high
dew points and can reduce the depression capability of the cooling
pump at very low dew points. Too much flow also accelerates the
rate of system contamination. A flow rate of 2 to 2.5 ft
over 1 liter/min) is ideal for most applications. In many cases, flow
rates between 0.2 and 5 ft
Sensor replacement
If it necessary to remove the sensor module, follow the steps below:
1. Disconnect the line power from the unit.
2. Open the front door.
3. Unplug the sensor cable from the end of the sensor probe as
shown in Figure 7.
4. Unscrew the four wing nuts shown in Figure 7.
5. Carefully remove the sensor module.
3
/h (a little
3
/h (0.1 and 2.5 liter/min) may be used.
13
Chapter 2 — Installation
14
E4-1111H-GE Operator’s Manual
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