isweek M1 Series User manual

M1 Series
humidity temperature transmitters
INSTRUCTION MANUAL

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CONTENTS
Overview.......................................................................................................................................4
Operation .....................................................................................................................................5
Power supply................................................................................................................................5
Operating range and limits .............................................................................................................5
Temperature compensation of the humidity sensor...........................................................................6
Output range.................................................................................................................................6
Installation....................................................................................................................................6
General recommendations .............................................................................................................6
Installation and wiring of the base plate...........................................................................................7
Measuring humidity or temperature only..........................................................................................9
Installation of the electronics module.............................................................................................10
Maintenance...............................................................................................................................10
Cleaning or replacing the dust filter ...............................................................................................10
Periodic calibration check............................................................................................................10
Service connector........................................................................................................................12
Service cable..............................................................................................................................13
Specifications .............................................................................................................................14
Appendix 1: Practical Advice for Measuring Humidity......................................................................15
Appendix 2: Calibration................................................................................................................15
Appendix 3: Accessories for the M1 Series ...................................................................................15
PLEASE, READ THIS FIRST
•Check the product for any physical damage that may have occurred during shipment. We
carefully pack and routinely insure all shipments. If any damage has occurred, it is your
responsibility to file a claim with the carrier, prior to returning the damaged product. Please
note that our warranty does not cover damage during shipment.
•Prior to installation, get fully familiarized with the operating limits of the product and with the
installation instructions provided in this manual.
•Do not remove the sensor protection (dust filter) from the probe. Both sensors (humidity and
temperature) can be mechanically damaged by careless removal of the protection.
•Identification labels (model number, output ranges, etc.): identification labels are located (a) on
the shipping box and (b) inside the electronics module, under the printed circuit board (pop out
the board to read the label).
Every instrument is carefully calibrated before shipment and should not require any further
adjustments before installation. If you have any question or problem, please call our service
department at 631/427-3898 and press 5 (or ask for extension 21).

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Overview
The M1 series are humidity and temperature transmitters suitable for cost sensitive applications where
conditions are within the range of 0 to 100 %RH and -30 to 70°C (-22 to 158°F). The M1 series
measures both humidity and temperature and can also be used to measure either humidity or
temperature only.
Linearized output signals (DC current or voltage) are provided for transmission over a length of cable to a
remote display, recorder, controller or data processing unit. Two types of electronic circuit are available:
2-wire, loop powered (4…20 mA current signal) and 3-wire (voltage or current signal).
Well proven sensors and a robust housing make the M1 series appropriate for use both in commercial
and in industrial applications. Digital signal processing within the M1 series ensures consistent product
performance and also facilitates the task of field maintenance with features such as potentiometer free –
digital calibration.
Main Features:
•relative humidity and temperature measurement
•available as 2-wire loop powered or as 3-wire circuit type
•well proven, durable humidity and temperature sensors
•potentiometer free –digital calibration
•test connector for communication with the HygroPalm 3 indicator 1)
1) allows the HygroPalm 3 to read and / or calibrate the transmitter
The M1 series features a unique installation method that is both convenient and problem free. Each M1
series transmitters includes a base plate and a plug-in electronics module. During installation, the base
plate is mounted first and wired without the electronics module. This is done at the same time as general
electrical work. During that time, the electronics module and probe can safely be stored away.
The M1 series was designed for simple field maintenance and to minimize any downtime:
-Operation of the M1 transmitter can be easily verified in the field by connecting a HygroPalm 3 indicator
to the M1 service connector. This is done without interrupting the output signals.
-Calibration is entirely digital, without any potentiometer.
-Should the electronic module develop a problem, it can easily be removed from the base plate and
replaced with another module without any wiring work.
The M1 series is available in the following configurations:
Model Measurement 1) Circuit Type Installation
M12W %RH + Temperature 2-wire, loop powered Wall mount
M12D %RH + Temperature 2-wire, loop powered Duct mount
(through Wall)
M13W %RH + Temperature 3-Wire Wall mount
M13D %RH + Temperature 3-Wire Duct mount
(through Wall)
1) The M1 series is also available for humidity or temperature measurement only

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Operation
Power supply
Depending on the circuit type, transmitters of the M1 series require the following supply voltage:
a) 2-wire (M12): 10..28 VDC (depending on the load connected to the output). The minimum supply
voltage can be determined as follows: V min = 10 V + 0.02 x Load (ohm). For the maximum load of
250Ω, the minimum supply voltage is 10 + 0.02 x 250 = 15 VDC. With both output circuits closed, the
maximum current consumption is 40 mA.
b) 3-wire (M13): 10 to 35 VDC (minimum 15 V for current outputs) or 12 to 24 VAC. With both output
circuits closed, the maximum current consumption is 50 mA.
Operating range and limits
The M1 series can operate within 0 to 99 %RH non condensing and -40 to 60°C (-40 to 140°F) at the
probe and electronics. The useful application range of the M1 series is 0 to 100%RH and -30 to 70°C
(-22 to 158°F) at the probe.
M12D / M13D
M12W / M13W
Dimensions in mm

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Operating the transmitter and/or its probe outside of the temperature operating limits can result
in permanent damage.
As far as possible, avoid sudden condensation at the sensors. When measuring at high humidity,
condensation may occur on the humidity sensor due to a sudden difference in temperature with the
environment. This does not damage the sensor. However, this will produce an overflow reading (an output
signal of more than 100 %RH) for as long as condensation is present on the humidity sensor.
Temperature compensation of the humidity sensor
Practically every make of relative humidity sensor requires a compensation for the effect of temperature
on the humidity output signal in order to measure accurately over a wide range of temperature conditions.
In the specific case of an instrument using a capacitive sensor, compensation is required because the
dielectric characteristics of both the water molecule and the hygroscopic polymer used in the sensor
vary with temperature.
The M1 series uses the temperature data from the Pt100 RTD to provide automatic compensation for the
effect of temperature on the humidity sensor. The temperature compensation uses normal room
temperature as a reference. Because of this, calibration of the M1 series is always done at normal room
temperature.
Output range
The standard range of the relative humidity output is 0 to 100%RH. Other ranges are available on
request. The temperature output depends on the range specified when ordering -see identification labels
(a) on shipping box and (b) on the transmitter enclosure.
Installation
Do not unnecessarily remove the dust filter from the probe. The sensors can easily be damaged
when not protected.
General recommendations
Relative humidity is extremely dependent on temperature. Proper measurement of relative humidity
requires that the probe and its sensors be at exactly the temperature of the environment to be measured.
Because of this, the location where you choose to install the probe can have a significant effect on the
performance of the instrument. The following guidelines should guarantee good instrument performance:
a) Select a representative location: install the probe where humidity, temperature and pressure
conditions are representative of the environment to be measured.
b) Provide good air movement at the probe: air velocity of at least 200 ft/ minute (1 meter/second)
facilitates adaptation of the probe to changing temperature.
c) Avoid the following: (1) Close proximity of the probe to a heating element, a cooling coil, a cold or
hot wall, direct exposure to sun rays, etc. (2) Close proximity of the probe to a steam injector, humidifier,
direct exposure to precipitation, etc. (3) Unstable pressure conditions resulting from excessive air
turbulence.

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d) Immerse as much of the probe as possible in the environment to be measured.
e) Prevent the accumulation of condensation water at the level of the sensor leads. Install the
probe so that the probe tip is looking downward. If this is not possible, install the probe horizontally.
Installation and wiring of the base plate
The base plate should be installed first, using screws with an approximate diameter of 5/32".
M12: 2-wire, loop powered
Base Plate Terminals Description
1 and 3
2
4
5and 6
10…35 VDC (+)
temperature output
relative humidity output
not used
Installation Note (through wall installation)
You may want to provide an orifice at a distance of about 3” from the probe of
the transmitter for future use by a reference probe and HygroPalm indicator.
The base plate of the M1 transmitter is supplied with one sealing cable grip
(normally, the base plate is installed with the cable grip on top). This cable
grip provides effective sealing only with cables having the proper outside
diameter. Preferably, use a cable with an outside diameter of 0.236 to 0.275
inch (6 to 7 mm) and with 18 AWG wires. Avoid running the cables
connecting the unit in the same conduit as 110 VAC power cables.
Depending on the installation, you may have to use a cable with twisted pairs
or a shielded cable to avoid electromagnetic interference.
V+ V+TRH

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Note: it is not necessary to connect both terminals 1 and 3 to the plus side of the power supply. The
transmitter will operate normally with just one of these terminals connected.

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M13: 3-wire
Base Plate Terminals Description
1
2
3
4
5 (+) and 6 (-)
10…35 VDC (+) or 24 VAC
common (-) 1)
Temperature (+) / Output 2
Humidity (+) / Output 1
Not Used
1) We generally recommend grounding, especially if the electronics will be subjected to a low humidity
environment (35 %RH or less).
In order to determine the maximum length of cable that can be used to connect the transmitter to other
devices, the first step is to find out what is the resistance per unit of length of the cable that you plan on
using.
.Current outputs: the maximum permissible cable length, connecting the unit to other devices, is
determined by the total resistance resulting from the addition of the cable resistance and that of the
devices connected in series with the unit. This resistance should not exceed 250 ohms.
.Voltage outputs: the maximum cable length can be determined under consideration of the voltage
drop caused by the current flowing to the devices connected to the unit. The voltage drop in the cable
depends both on cable resistance and on the equivalent resistance of the devices connected in
parallel to the unit. The total resistance connected to each unit output must at least be equal to 1000
ohms. Cable resistance should not be more than 1/1000 of the load resistance.
Measuring humidity or temperature only
M12 (2-wire, loop powered): the transmitter can be factory configured to allow one of the two current
loops to remain open (please specify which output will be used when ordering). Without this special
configuration, both current loops should be closed.
Voltage Outputs
Current Outputs
Common (GND)
RH
T
DC +
or
Phase
Not Used

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M13 (3-wire): the humidity and temperature circuits are independent one from the other. Any output can
be operated without closing the loop for the other output.
Installation of the electronics module
Maintenance
Cleaning or replacing the dust filter
The dust filter should be cleaned from time to time, depending on the conditions of measurement.
Cleaning should be done without removing the filter from the probe. Clean the filter with a fine brush. If
this is not sufficient, the filter should be replaced. To do this, unscrew the filter from the probe.
Before putting on a new dust filter, check the alignment of both sensors with the probe. The wires that
connect the sensors to the probe are very thin and bend easily. If this happens, correct the alignment by
holding the sensor very gently with a pair of small flat nosed pliers.
Periodic calibration check
Long term stability of the ROTRONIC Hygromer humidity sensor is typically better than 1 %RH per
year. For maximum accuracy, calibration of the probe should be verified every 6 to 12 months.
Applications where the probe is exposed to significant pollution may require more frequent
verifications.
Both the Pt 100 RTD temperature sensor and associated electronics are very stable and should not
require any calibration after the initial factory adjustment.
Once the base plate has been
installed and wired, the
electronics module can be
inserted and secured with the
screws provided. The
transmitter is ready to operate.

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For routine calibration checks, the probe should be verified at one or two values of humidity. For
more details, see service connector, service cable and appendix 2 -calibration.