General Eastern Dew-10 Operating Manual

DEW-10 DEW POINT TRANSMITTER GUIDE

For Information in th is ma n ual is believed to be rel i-
able. However, GE Infrastructure Sensing makes no warranty,

expressed or implied, as t o its accuracy and assumes
no liability arising out of its use by others. We reserve
the right to change this manual without prior notice,

1-24-1992
PART NO. A40096273/B.00 ECO NO.2114
Copyright  1999 GE Infrastructure Sensing

TABLE OF CONTENTS

INTRODUCTION TO DEW-10 DEW POINT TRANSMITTER .................................................4

PERFORMANCE AND OPERATING RANGES .........................................................................4

TO SPECIFY POWER/SIGNAL/CONFIGURATION OF DEW-10 TRANSMITTER................5

INSTALLATION OF DEW-10 - XX0: WALL MOUNT.............................................................. 6

Installation Hint ..................................................................................................................6

INSTALLATION OF DEW-10 - XX1: DUCT MOUNT.............................................................. 7

Installation Hints..................................................................................................................7

INSTALLATION OF DEW-10 - XX2: PIPE MOUNT.................................................................8

Installation Hints..................................................................................................................8

WIRING GUIDE FOR THE DEW-10............................................................................................9

Power Connections..............................................................................................................9

Signal connections for DEW POINT ..................................................................................9

Signal connections for AIR TEMPERATURE (on wall mount only) ..............................10

Conversion of Internal Transmitter to Loop Power...........................................................10

Connection of Internal Transmitters to PCB No. ..............................................................10

Listing of Terminal and Connector Designations..............................................................11

REQUIREMENT FOR PERIODIC MAINTENANCE................................................................13

DESCRIPTION OF DEW-10 TRANSMITTER SUBASSEMBLIES..........................................14

PCB No. 1 Subassembly....................................................................................................14

PCB No.2 Subassembly.....................................................................................................14

Sensor Subassembly ..........................................................................................................14

PERIODIC MAINTENANCE PROCEDURES............................................................................15

PROCEDURE FOR MIRROR SURFACE CONDITION CHECK.............................................15

PROCEDURE FOR MIRROR SURFACE CLEANING..............................................................16

PROCEDURE FOR FINE OPTICAL BALANCE ADJUSTMENT............................................16

COARSE BIAS ADJUSTMENT PROCEDURE .........................................................................17

TABLE OF CONTENTS

(continued)

DIAGNOSTIC PROCEDURES FOR DEW-10 TRANSMITTER SUBASSEMBLIES..............18

Diagnostics for PCB No. 1.............................................................................................................18

Diagnostics for PCB No. 2.............................................................................................................18

Diagnostics for Sensor...................................................................................................................18

Diagnostics for Internal Transmitter ........................................................................................... ...18

Quick Calibration Check................................................................................................................19

Trouble Shooting Guide.................................................................................................................19

IDENTIFICATION OF SUBASSEMBLIES AND PARTS.........................................................20

Common parts to DEW-10 Transmitter.........................................................................................20

INSTRUMENT PRODUCTS WARRANTY POLICY ................................................................21

PRODUCT RETURN PROCEDURE...........................................................................................22

INTRODUCTION TO DEW-10 DEW POINT TRANSMII1ER

The DEW-10 Series is a family of low-cost, high-performance chilled mirror dew point
transmitters. In the sensor a metal mirror surface is controlled at the dew point - the temperature
at which water vapor condenses from the surrounding air. The temperature of the mirror is
continuously measured by a platinum resistance thermometer (PRT). The measurement is
available directly as resistance or may be internally converted to an analog signal. For the wall
configuration only, an air temperature probe may be integrated into the unit.

The measurements of dew point and air temperature are stable, accurate and traceable to
National standards. As long as the Transmitter is in good working order, outputs are accurate to
+/- 0.5 degrees Celsius. The calibration of each PRT is confirmed by GE Infrastructure Sensing
Instruments against transfer standards calibrated by the National Institute of Standards and
Technology (formerly NBS). Each transmitter comes with the full support that GE Infrastructure
Sensing offers for all its products.

PERFORMANCE AND OPERATING RANGES

Mirror depression: 40 C (72 F) at 25 C (77 F) ambient

(See Operating Range Diagram)

Accuracy: +/- 0.5 C (+/- 1.0 F)

Repeatability: +/- 0.05 C (+/- 0.1 F)

Response Time: 2 minutes max for one time constant at 100 meters/300 feet per

minute

Environmental Limits
Min/Max Sensor: -lOCto70C(OF to 160F)
Min/Max Electronics: 0 C to 60 C (32 F to 120 F)
Flow Rate: 100 to 1000 meters (300 to 3000 feet) per minute for duct/pipe
Max. Pressure: 0 to 300 mbar (0 to 5 psig)

Power Requirements
Standard Power: 24 +/- 6 VDC at 350 mA
Optional Power: 24/115/230 VAC +/- 10% 50/60 Hz 10 VA

Available Output Signal
Standard output: DIN 43760 4-wire PRT (100 Ohms @ 0 C)
Optional output: Linear 4-20mA/1-5VDC loop/source powered

Dimensions
Shipping Weight: 10 pounds
Dry Weight: 6 pounds
Shipping Dimensions: 14” x 6” x 20”

TO SPECIlY POWER/SIGNAL/CONFIGURATION OF DEW-10

DEW-

10

P

S

C

TRANSMITTER

(0) 24 VDC (A) 4 wire PRT
(0) Wall Mount
Standard Standard

(1) 24 VAC (B) 4 –20
(1) Duct Mount
0-100 F

(2) 115 VAC (C) 4-20 mA
(2) Pipe Mount

(3) 230 VAC (D) 4-20 mA

-40-140 F

-40-60 C

(X) 4-020 mA
User Selected

Identify your Dew-10 specifications:

DEW-10 –

POWER SIGNAL
CONFIGURATION

OWER

IGNAL

ONFIGURATION

INSTALLATION OF THE DEW-10 - XX0: WALL MOUNT

(

1) Identify installation point. Unit is mounted with chassis against wall and metal cap or
optional air temperature probe toward floor. Avoid detectable down drafts and allow easy
access for periodic maintenance.

(2) Remove plastic cover and use holes in chassis as template for locating mounting screws.

The plastic cover is attached to chassis by velcro strips. To remove cover, pull away from
chassis.

(3) Wire according to guide that follows installation instructions. Unit will power up

immediately upon connection to power.

(4) Check operation by moving switch SW1 on PCB No. 1 to CHECK position. LED should

light within two minutes to confirm that unit can operate correctly. If LED does not light
see trouble shooting guide. If LED does light return SW1 to OPERATE position. LED
will go out as dew condenses on the metal mirror in the sensor.

(5) Replace plastic cover.

Installation Hint

As air is sampled by convection currents through the sensor cavity, the transmitter is sensitive to
down drafts and orientation. If down drafts cannot be eliminated a baffle may be mounted above
the transmitter to deflect the air flow around unit

INSTALLATION OF DEW-10 - XX1: DUCT MOUNT

(

1) Identify installation point. Flow through duct at location should be non-turbulent at a rate
of 100 to 1000 meters (300 to 3000 feet) per minute. Location should allow removal of
unit from duct for periodic maintenance.

(2) Remove duct mounting plate from unit and use as template to locate mounting screws.

An access hole through the duct wall of 1.25 inches(3.25 cm) diem. at the center of the
installation point is required to insert the sensor into the duct.

(3) Install duct mounting plate to duct wall. Insert sensor through duct wall and secure unit to

the plate.

(4) Gain access to PCB No. 1 by removing one screw holding back cover of electronics

housing. Loosen second screw and pivot cover and gasket around this screw. Wire
according to guide following installation instructions. Unit will power up immediately
upon connection of power.

(5) Check operation by moving switch SW1 on PCB No. 1 to CHECK position. LED should

light within two minutes to confirm that unit can operate correctly. If LED does not light
see trouble shooting guide. If LED does light return SW1 to OPERATE position. LED
will go out as dew condenses on the metal mirror in the sensor.

(6) Replace back cover.

Installation Hints

The sampling system of the unit requires non-turbulent flow between 100 and 1000 meters (300
to 3000 feet) per minute. Avoid plenums, dampers, turns, etc. that create turbulent flow or
manifolds with dead flow zones. The unit is shipped with an air sample flow choke positioned
for maximum flow through the sensor cavity. If high flow rates through the duct cause excessive
signal oscillation, remove the sensor shield and move the slot in the choke above the sensor
cavity counterclockwise to reduce flow through the sensor.

Install the unit well downstream of air washers or steam injectors as water carryover can flood
and damage the sensor.

Avoid installation points with negative pressure relative to outside the duct such as at a fan inlet
as the unit is not pressure tight. Air may be drawn through the electronics housing into the
sample cavity making incorrect dew point measurements.

INSTALLATION OF DEW-10 – XX2: PIPE MOUNT

(

1) Identify installation point. Flow through duct at location should be non-turbulent at a rate
of 100 to 1000 meters (300 to 3000 feet) per minute. Location should allow for unit to be
removed for periodic maintenance.

(2) Mount a pipe flange with a female one inch NPT thread for the male compression fitting

on the sensor.

(3) Position the compression fitting just below the sensor shield. Insert the sensor into the

flange and screw in the compression fitting. Hand-tighten until the sensor is secure. Hold
the electronics housing in the desired orientation and tighten the compression fitting until
the sensor is held securely in place.

(4) Gain access to PCB No. 1 by removing one screw holding back cover of housing. Loosen

second screw and pivot cover and gasket around this screw. Wire according to guide in
next section. Unit will power up upon connection of power.

(5) Check operation by moving switch SW1 on PCB No. 1 to CHECK position. LED should

light within two minutes to confirm that unit can operate correctly. If LED does not light
see trouble shooting guide. If LED does light return SW1 to OPERATE position. LED
will go out as dew condenses on the metal mirror in the sensor.

(6) Replace back cover.

Installation Hints

The sampling system of the unit requires non-turbulent flow between 100 and 1000 meters (300
to 3000 feet) per minute. Avoid plenums, dampers, turns, etc. that create turbulent flow or
manifolds with dead flow zones. The unit is shipped with an air sample flow choke positioned
for maximum flow through the sensor cavity. If high flow rates through the duct cause excessive
signal oscillation, remove the sensor shield and move the slot in the choke above the sensor
cavity counterclockwise to reduce flow through the sensor.

Install the unit well downstream of air washers or steam injectors as water carryover can flood
and damage the sensor.

Avoid installation points with negative pressure relative to ambient conditions such as a fan inlet
as the unit is not pressure tight.

The shield may be removed for flow rates below 1 liter per minute or 5 cubic feet per hour if
ambient light is prevented from entering the sample cavity. Consult factory for additional
support. A sample system for this application is available.

WIRING GUIDE FOR THE DEW-10

This Guide is for DEW-10 with PCB No.1 having a ten terminal strip for electrical connections,
all versions of PCB No.2 and all internal transmitters. The controller circuit, PCB No. l, operates
on 18 to 30 VDC at 350 mA maximum. The transformer PCB No.2, converts 24/115/230 VAC
to 24 VDC to power PCB No. 1. The standard output for dew point and air temperature as an
option on the wall configuration is four-wire PRT. Internal transmitters to provide linear analog
signals are available as loop or source powered. All the wiring to the DEW-10 should be 22
AWG.

Power Connections

For 24 VDC to unit connect leads to ten terminal strip (connector P4) on PCB No. 1.

Terminal 8 24 VDC in
Terminal 10 24 VDC return

For 24/115/230 VAC to unit connect leads to two terminal strip on PCB No. 2.

Terminal 1 VAC in
Terminal 2 VAC return
Card Cage Lug VAC common

Signal connections for DEW POINT

For dew point as four-wire RTD output connect leads to ten terminal strip (connector P4) on
PCB No. 1 or to the six terminal connector P3.

P4 P3

Terminal 1 Terminal 5 High
Terminal 2 Terminal 6 High
Terminal 3 Terminal 3 Low
Terminal 4 Terminal 4 Low

For dew point as linear 420 mA signal connect leads to ten terminal strip (connector P4) on
PCB No. 1.

Terminal 5 signal out

Terminal 10 signal return

For 1-5 VDC signal make same connections and connect 250 Ohm resistor across load
terminals.

Signal connections for AIR TEMPERATURE (on wall mount only)

For air temperature as four-wire RTD output connect leads to six terminal connector P2 on
PCB No. 1.

P2

Terminal 5 High
Terminal 6 High
Terminal 3 Low
Terminal 4 Low

For air temperature as linear 4-20 mA signal connect leads to ten terminal strip (connector
P4) on PCB No.1.

Terminal 6 signal out
Terminal 10 signal return

For 1-5 VDC signal make same connections and connect 250 Ohm resistor across load
terminals.

Conversion of Internal Transmitter to Loop Power

Internal transmitter configured at factory as source powered unless specified as loop powered at
time of order. Cut jumper J1 on edge of PCB No. 1 as identified on attached drawing. Connect
leads to ten terminal strip on PCB No. 1.

For dew point connect leads as follows:

Terminal 5 signal return
Terminal 7 20 mA power in

For air temperature connect leads as follows:

Terminal 6 signal return
Terminal 7 20 mA power in

Connection of Internal Transmitters to PCB No. 1

The internal transmitters accept four-wire PRT output and convert it to a linear 4-20 mA signal
that spans a preset temperature. The transmitter for dew point may be wired to the ten terminal
strip P4 or to the six pin connector P3. The transmitter for air temperature is wired to the six pin
connector P2. The leads are color coded.

For dew point connect transmitter leads as follows:

Transmitter PCB No.1
Lead Color Connection

Red P4 Term. 7 P3 Term. 1 Power in
Black P4 Term. 5 P3 Term. 2 Signal return
Green P4 Term. 1 P3 Term. 3 High
Yellow P4 Term. 2 P3 Term. 4 High
Blue P4 Term. 3 P3 Term. 5 Low
Violet P4 Term. 4 P3 Term. 6 Low

For air temperature connect transmitter leads as follows:

Transmitter PCB No.1
Lead Color Connection

Red P2 Term. 1 Power in
Black P2 Term. 2 Signal return
Green P2 Term. 3 High
Yellow P2 Term. 4 High
Blue P2 Term. 5 Low
Violet P2 Term. 6 Low

Listing of Terminal and Connector Designations

PCB No. 1 Ten Terminal Strip (P4)

Terminal Designation

1 PRT high for dew point
2 PRT high for dew point
3 PRT low for dew point
4 PRT low for dew point
5 Linear 4 to 20 mA out for dew point
6 Linear 4 to 20 mA out for air temp
7 power in for internal transmitter
8 24VDC power in for PCB No. 1
9 Chassis ground
10 24VDC power out from PCB No. 1

PCB No. 1 Internal Transmitter Connectors (P3 & P2)

Connector P3 Designation

1 PRT high for dew point
2 PRT high for dew point
3 PRT low for dew point
4 PRT low for dew point
5 Linear 4 to 20 mA out for dew point
6 Linear 4 to 20 mA out for air temp.

Connector P2 Designation

1 PRT high for air temperature
2 PRT high for air temperature
3 PRT low for air temperature
4 PRT low for air temperature
5 power to internal transmitter
6 signal output of transmitter

PCB No.2 Incoming AC Power and 24VDC to PCB No. 1

AC Connector Designation

1 AC power high
2 AC power low

24VDC Leads Connection to PCB No. 1

red Terminal 8 24VDC power in
black Terminal 10 24VDC power return

REQUIREMENT FOR PERIODIC MAINTENANCE

The DEW-10 Transmitter utilizes a chilled mirror sensor to measure dew point - the temperature
at which water vapor condenses from the surrounding air. The control of the mirror surface is
done automatically by comparing the intensity of a reference light bridge to the primary bridge
that reflects light across the surface of the mirror. A thermoelectric heat pump under the mirror
reduces its temperature to the dew point. Condensed water vapor scatters light reflected across
the mirror reducing the intensity of the primary light bridge. The electronics in the transmitter
controls the heat pump to maintain a constant difference in reference to primary light intensity
keeping the mirror at the dew point. The temperature of the mirror is continuously measured by a
platinum resistance thermometer (PRT) with the measurement available as resistance or
optionally as a linear analog signal.

The ability of the DEW-10 Transmitter to control the mirror at the dew point is dependent on the
mirror surface condition and the optical balance of the primary and reference light bridges.
Contaminants trapped in dew on the mirror may alter the dew point at its surface as well as
reduce its reflectance. The optical balance performed at the factory may be altered by a physical
change in the mirror surface as well as aging of the optical components. The mirror condition
and optical balance must be checked regularly and serviced if required.

Service checks should be performed each month though the period is specific to the installation.
A service kit with cotton swabs and cleaning solution to clean the mirror and a screwdriver to
adjust the optical balance as well as fuses and O-rings is included with each order. Additional
kits and parts as listed in the Recommended Service Parts section may be purchased directly
from GE Infrastructure Sensing .

DESCRIPTION OF DEW-10 TRANSMITTER SUBASSEMBLIES

The electronics housing contains the printed circuit board that controls the chilled mirror sensor
(PCB No. l) as well as an optional transformer board to convert AC power to 24 VDC (PCB
No.2) and internal transmitters to convert resistance outputs of the PRTs to linear analog signals.

PCB No. 1 Subassembly

Wiring to PCB No. 1 is connected to the ten terminal strip on the edge of the board. Next to this
strip is a blue component with a brass screw head called the trimpot. In front of the trimpot is a
light emitting diode (LED) referred to in the following procedures. At the corner of PCB No. 1
on this edge is a three position slide switch (SW1) to control the operating mode of the
Transmitter. The center position is the normal operating mode - OP - with the position closest to
the corner of PCB No. 1 as the optics balance mode - BAL - and the position closest to the
terminal strip as the mirror check mode - CHK. Moving SW1 to either end position disables the
thermoelectric heat pump allowing the mirror to warm to air temperature. See the PCB No. 1
drawing for greater detail.

PCB No.2 Subassembly

The transformer board (PCB No.2) accepts 24/115/230 VAC +/- 10 % and converts it to 24VDC
to power PCB No. 1. Consult the wiring guide for specific connections to PCB No.2. The two
leads from PCB No.2 must be connected to the ten terminal strip of PCB No. 1 at terminals 8 and

10. The fuse is rated at 250 mA and 250 volts.

Sensor Subassembly

The components of the chilled mirror sensor are in the sensor cavity. The sensor cavity may be
accessed in the duct and pipe configurations by sliding the shield away from the electronics
housing while access to the cavity in the wall configuration requires that the plastic cover be
pulled from the chassis and that the sintered bronze filter be removed. The mirror is a tiny metal
reflector on top of the black plastic-coated pyramid mounted at a 45 degree angle.

Drawings of each subassembly follow.

PERIODIC MAINTENANCE PROCEDURES

Unit should be powered to perform maintenance procedures.

PROCEDURE FOR MIRROR SURFACE CONDITION CHECK

(1) Gain access to PCB No. 1

Duct/pipe configuration: Remove one screw from the back cover. Loosen the other

screw. Pivot the cover and gasket around the loose screw to
expose the edge of PCB No. 1.

Wall configuration: Plastic front cover is mounted to the transmitter chassis by velcro

tabs. Pull the cover away from the chassis.

(2) Locate SW1 on PCB No. 1. SW1 is in OP position.

(3) Move SW1 to CHK position. Wait 120 seconds for LED next to SW1 to light.

(4) If LED lights then mirror condition is acceptable. Return SW1 to OP position. Replace

cover.

(4a) If LED does not light then perform the mirror cleaning procedure.

PROCEDURE FOR MIRROR SURFACE CLEANING

Cotton swabs and cleaning solution (methanol with distilled water) are in the service kit.

(1) Gain access to PCB No. 1 (See mirror check procedure).

(2) Move SW1 to CHK position.

(3) Gain access to the sensor cavity.

Duct/pipe configuration: Remove sensor from duct or pipe. Pull shield away from electronics
housing.

Wall conf~guration: Remove plastic cover by pulling away from velcro tabs on chassis.
Remove sintered bronze filter.

(4) Locate mirror surface in the sensor cavity. Soak cotton swab in cleaning solution and

wipe across mirror. Dry mirror with second swab.

(5) Return shield or filter to original position.

(6) If LED lights move SW1 to operate OP. Replace cover.

(6a) If LED does not light perform fine optical balance adjustment procedure.

(7) For duct/pipe configuration reinsert sensor in-line and secure transmitter.

PROCEDURE FOR FINE OPTICAL BALANCE ADJUSTMENT

With this procedure the intensity of the primary light bridge is matched to the light intensity of
the reference bridge. The mirror should be clear and dry and ambient light must be prevented
from entering the sensor cavity during the adjustment.

(1) Gain access to PCB No. 1 (See mirror check procedure).

(2) Move SW1 switch to BAL position. Clean mirror according to mirror cleaning procedure.

Replace filter for wall configuration or shield for duct/pipe configuration to block
ambient light from sensor cavity.

(3) Turn trimpot clockwise to light the LED and counterclockwise to turn the LED off. Turn

the trimpot until LED just lights. If trimpot adjustment does not light LED then perform
the Coarse Bias Adjustment that follows.

(4) Move SW1 to the operate position. LED should go out within 40 seconds as dew is

condensed on the mirror. If LED does not go out replace PCB No. 1 and perform this
procedure again.

COARSE BIAS ADJUSTMENT PROCEDURE

This procedure is to adjust the intensity of the reference light bridge to be within the range of the
trimpot that controls the intensity of the primary light bridge. This field procedure makes the
sensor compatible the different versions of PCB No. 1 The mirror should be clear and dry and
ambient light must be prevented from entering the sensor cavity during the adjustment.

1) Gain access to PCB No. 1 (see mirror check procedure).

2) Identify each wire connection by wire color and terminal number. Disconnect PCB No. 1
and replace with new board. Reconnect wires.

3) Perform the mirror cleaning procedure. To block ambient light replace filter over cavity
of wall configuration or shield over cavity of duct/pipe mount.

4) At PCB No. l, move switch SW1 to the BAL position. Power to the thermoelectric
heatpump is interrupted allowing the mirror to warm to ambient temperature. Turn the
screwhead of the trimpot next to the LED counterclockwise until it gives an audible click
as it is turned through the end of its range. If the LED lights then no coarse adjustment is
required.

5) Identify the coarse bias adjustment screw above sensor cavity. The screw is aluminum
and requires a 1/16 inch Allen wrench to be adjusted. Block light from entering the
sensor cavity and turn screw clockwise and counterclockwise until LED on PCB No. 1
just lights. Then turn screw so that LED is just extinguished.

6) Perform fine optical adjustment procedure.

DIAGNOSTIC PROCEDURES FOR DEW-10 TRANSMITTER

SUBASSEMBLIES

For these procedures the DEW-10 is powered and SW1 is in the operate position. A
volt/Ohm/Ammeter is required.

Diagnostics for PCB No.1

DC Power Supply: Check the voltage across terminals 8 and 10 of the ten terminal strip on PCB

No.1 for 24 +/- 6 VDC. This voltage powers PCB No.1 and sensor.

If voltage is out of range check power supply and capture of power leads in terminal strip.
Replace PCB No.1.

Primary Optics Voltage: Check voltage across pin 5 of LM324 (Z1) and power loop return

(terminal 10 of terminal strip) for 2.3 to 2.7 VDC. Move SW1 to BAL position
and wait 120 seconds. Voltage should be 3.1 VDC maximum.

If voltage with SW1 in OP position is out of range return unit to factory for service or replace
sensor. If voltage with SW1 in BAL position is out of range adjust trim pot so that voltage falls
within range. If voltage is in range but LED does not light then return unit to factory for service
or replace PCB No.1.

Diagnostics for PCB No 2

Power Loop: Check voltage input across terminals 1 and 2 of two terminal strip for appropriate

input voltage. Check output leads for 24 VDC.

If voltage in or out is out of range then check power supply or connection of leads to terminal
strip. Also check fuse. Replace fuse if open. Replace board if fuse is good.

Diagnostics for Sensor

Four-Wire PRT Dew Point Output: Disconnect the optional temperature transmitter at PCB No.1

If PRT shows discontinuity or resistance output is inconsistent with ambient temperature return
sensor to factory for service.

connector P3 or if connected to ten terminal strip record
terminal connections and remove from strip. Check
continuity across terminals 2 and 3 of terminal strip. Measure
resistance across these terminals. DIN Standard 43760 PRT
provides resistance of 100 Ohms at 0 C with a change of

0.385 Ohms per 1 degree C. As examples, the PRT would
have a resistance of 103.85 Ohms at 10 degrees Celsius and

96.15 Ohms at -10 degrees Celsius.

Diagnostics for Internal Transmitter

This check compares the 4-Wire PRT resistance to the internal transmitter output at the dew
point and air temperature. The measurements for air temperature may be checked against an air
temperature thermometer.
Record the analog signal with SW1 in the operate position. Move SW1 to the mirror check
position and record the signal when the LED lights. See 4-wire PRT output diagnostic to
disconnect the internal transmitter. Record the resistance output of the PRT across terminals 2
and 3. Move SW1 to operate position and record the resistance output forty seconds after the
LED goes out. Convert resistances to temperatures. The calculated temperatures for dew point
and ambient temperatures from the PRT should match within +/-0.5øC (+/-1.0 F) to the
temperatures from the internal transmitter signal.

Ouick Calibration Check

Move switch SW1 on PCB No.1 to CHK position. Power to the thermoelectric heatpump is
interrupted. The mirror warms to ambient temperature in 120 seconds. Compare the dew point
output to a reliable air temperature probe. The two temperatures should agree within 1.0 C (2.0
F).

Trouble Shooting Guide

To check for symptoms attach ammeter for linear 4 to 20 mA signal at terminals 5 and 10 of ten
terminal strip on PCB No.1 with unit under power. If 4Äwire PRT output is taken from the unit
then check the resistance across terminals 2 and 3 of the ten terminal strip.

Symptom Response
(1) Zero Analog Output Check power to PCB No 2
Zero PRT Output Check power to PCB No 1
Check 4Äwire PRT for continuity

If all check out then internal transmitter requires factory
service.

(2) Oscillating Output Perform mirror cleaning
Adjust optical balance

For duct/pipe unit confirm that air flow past sensor is non­turbulent and is above 100 meter (300 feet) per minute.
If all check out then contact factory for service.

(3) 4 mA Output only Clean mirror

Low PRT Output Adjust optical balance

Confirm that air flow past sensor is non-turbulent and is
above 100 meter (300 feet) per minute. Put sensor back into
service and observe LED. If LED remains on then dew
point is out of sensor range. If minimum output persists
return to factory for service.

(4) 20 mA Output only Check 4-wire PRT for continuity

infinite PRT Output

(5) Output tracks Check SW1 and move to OP position
ambient temperature Check power to PCB No.2
Check power to PCB No.1
Check 4-wire PRT for continuity

If all check out then internal transmitter requires factory
service.

For other symptoms contact your local sales rep or an applications engineer at GE Infrastructure
Sensing at 1-800-225-3208.

IDENTIFICATION OF SUBASSEMBLIES AND PARTS

Common parts to DEW-10 Transmitter

GEI P/N DESCRIPTION

C40095333 PCB No.1 with ten terminal strip

C40057564 Wall Mount Transformer Board (PCB #2) 24 VAC
C40057556 Wall Mount Transformer Board (PCB #2) 115 VAC
P40101081 Wall Mount Transformer Board (PCB #2) 230 VAC
C40003444 Duct Mount Transformer Board (PCB #2) 24 VAC
C40003089 Duct Mount Transformer Board (PCB #2) 115 VAC
P40101099 Duct Mount Transformer Board (PCB #2) 230 VAC

P40101172 Transmitter, 4-20mA (1Ä5 VDC), 0 to 100°F
P40101214 Transmitter, 4-20mA (1Ä5 VDC), 0 to 50°C
P40101198 Transmitter, 4-20mA (1Ä5 VDC), -40 to 140°F
P40101230 Transmitter, 4-20mA (1Ä5 VDC), user selected range

P70000454 Wall Mount Sensor Assembly
P70001055 Wall Mount Sensor Assembly with Air Temp.
P70000445 Duct/Pipe Mount Sensor Assembly

B40055386 Sensor Maintenance Kit for Wall Mount
P40055592 Six sintered bronze replacement filters

B40050403 Sensor Maintenance Kit for Duct/Pipe Mount
P40055543 Six sintered bronze replacement filters

A40096273 DEW-10 Manual

INSTRUMENT PRODUCTS WARRANTY POLICY

GE Infrastructure Sensing warrants equipment of its manufacture against defective materials or
workmanship for a period of one year from date of shipment.

Liability of the Seller under this warranty is limited, at Seller's option, to:

• Repair or replacement of defective parts at no charge.

• Credit adjustment, not to exceed original equipment sales price.

This warranty is subject to the following conditions:

• Prompt notification to Seller upon discovery of defects or missing items.

• Obtaining return authorization number from Seller to return defective items to plant

as directed.

• Return of equipment, freight charges pre-paid, or as otherwise agreed.

Defects caused by negligence, misuse, improper installation, accident or unauthorized repair or
alternation by buyer or user, or any modification, such as changing range resistors, may void this
warranty.

This warranty does not include mechanical parts failing from normal usage nor does it cover
limited life electrical components which deteriorate with age.

This warranty is in lieu of all other warranties, expressed or implied, including the implied
warranty of fitness for a particular purpose to the original purchaser or to any other person. Seller
shall not be liable for consequential damages of any kind.

Damage shipments: In case of shipping damage, it is the Buyer's responsibility to file a claim.
The customer should inspect the shipping container upon receiving and note any evidence of
damage of the freight receipt. If concealed damage is found after opening the container, the
customer should file a claim with the carrier at once. The customer must retain the shipping
container and all materials.

Repaired equipment: All repairs are warranted for 1 year. Only the repairs and components
replaced as part of these repairs are covered by this warranty. Other repairs or defective parts are
covered by the original warranty if applicable.

PRODUCT RETURN PROCEDURE

All GE Infrastructure Sensing are fully tested and calibrated prior to shipment. Should a
problem with the operation of the equipment arise, the following procedure must be followed:

1. Contact the factory* to discuss the problem. Sometimes a problem can be re-

solved by a change in operating procedure or an adjustment to the equipment.

2. If the equipment must be returned to the factory, a Return Authorization number

must be obtained from GE Infrastructure Sensing and referenced on the return
shipping papers. A written description of the problem should also be included.

3. If equipment is not covered by GE Infrastructure Sensing's Warranty Policy, a

purchase order should be submitted with the equipment returned. The order
should cover one of the following:

a. Open order, authorizing repair of equipment to meet published specs.

Repair costs will be billed on actual cost basis, but will not exceed 50% of
replacement cost without prior customer approval.

b. Order for not to exceed $500.00 or 30% of replacement cost, whichever is

higher. If repair costs exceed this amount, customer will be quoted cost
before work is done.

c. Order to cover cost of test and evaluation only. Amount based on type of

equipment returned. GE Infrastructure Sensing will evaluate but not repair
the unit. GE Infrastructure Sensing will call customer to discuss evaluation
and quote cost of repair or replacement.

To expedite repairs and reduce costs, options a) and b) are recommended.

4. After receiving a Return Authorization number, the equipment must be returned

freight PREPAID.

5. GE Infrastructure Sensing reserves the right to apply a minimum service charge in

cases where an instrument is returned for repairs or recalibration but does not
require service.

Return of equipment without a Return Authorization number and Purchase Order would
significantly delay turn-around time and incur additional costs. To expedite repairs and reduce
costs, all stipulations above should be followed.

NOTE: GE Infrastructure Sensing guarantees N.I.S.T. traceability and operation within stated
specifications. However, claims regarding accuracy or traceability will be covered under
warranty only when verified at GE Infrastructure Sensing, or by a fully independent testing

laboratory. Examples of independent labs are: N.I.S.T. (U.S.), N.P.L. (U.K.), SIRA Institute
(U.K.), and C.E.T.I.A.T. (France). For a list of other independent labs, contact GE Infrastructure
Sensing*.

* For countries other than the U.S., the local agent may also be contacted.