Vaisala MHT410 User Manual
M211737EN-H
User Guide
Vaisala Moisture, Hydrogen and Temperature
Transmitter for Transformer Oil
MHT410
PUBLISHED BY
Vaisala Oyj
Vanha Nurmijärventie 21, FI-01670 Vantaa, Finland
P.O. Box 26, FI-00421 Helsinki, Finland
+358 9 8949 1
Visit our Internet pages at www.vaisala.com.
© Vaisala 2021
No part of this document may be
reproduced, published or publicly
displayed in any form or by any means,
electronic or mechanical (including
photocopying), nor may its contents be
modified, translated, adapted, sold or
disclosed to a third party without prior
written permission of the copyright holder.
Translated documents and translated
portions of multilingual documents are
based on the original English versions. In
ambiguous cases, the English versions are
applicable, not the translations.
The contents of this document are subject
to change without prior notice.
Local rules and regulations may vary and
they shall take precedence over the
information contained in this document.
Vaisala makes no representations on this
document’s compliance with the local
rules and regulations applicable at any
given time, and hereby disclaims any and
all responsibilities related thereto.
This document does not create any legally
binding obligations for Vaisala towards
customers or end users. All legally binding
obligations and agreements are included
exclusively in the applicable supply
contract or the General Conditions of Sale
and General Conditions of Service of
Vaisala.
This product contains software developed
by Vaisala or third parties. Use of the
software is governed by license terms and
conditions included in the applicable
supply contract or, in the absence of
separate license terms and conditions, by
the General License Conditions of Vaisala
Group.
Table of contents
Table of contents
1. Safety................................................................................................................... 7
1.1 ESD protection.................................................................................................. 8
2. About this document.....................................................................................9
2.1 Documentation conventions..........................................................................10
2.2 Regulatory statements................................................................................... 10
2.2.1 FCC Part 15 compliance statement........................................................10
2.3 Trademarks........................................................................................................11
3. Product overview...........................................................................................12
3.1 Main features....................................................................................................12
3.2 Product parts and package contents............................................................13
3.3 Measurement parameters and units..............................................................15
3.4 Oil types............................................................................................................16
3.4.1 Oil type information in order code.........................................................16
3.4.2 Oil-specific coecients for ppmw moisture measurement................ 16
3.5 Data logging.....................................................................................................17
3.6 Status LEDs...................................................................................................... 17
4. Installation........................................................................................................ 19
4.1 Planning the installation................................................................................. 19
4.1.1 Recommended installation locations...................................................20
4.2 Mechanical installation....................................................................................21
4.3 Electrical installation......................................................................................28
4.4 Loop-powered display.................................................................................... 31
4.4.1 Wiring the loop-powered display..........................................................32
4.5 Checklist after installation............................................................................. 33
4.6 Oil fittings check after installation............................................................... 34
4.7 Removing the transmitter............................................................................. 34
4.8 Re-installing the transmitter in new location..............................................35
5. Analog output................................................................................................ 37
5.1 Analog output overrange behavior..............................................................37
6. Modbus............................................................................................................. 39
6.1 Overview of Modbus protocol support........................................................39
7. Vaisala Industrial Protocol........................................................................40
7.1 Connecting to MHT410 via service port........................................................41
7.1.1 Installing driver for the USB service cable............................................ 41
7.1.2 Connecting USB service cable...............................................................42
7.1.3 Configuring terminal application settings........................................... 42
7.2 Serial commands summary.......................................................................... 44
7.3 Device information and status commands................................................. 46
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MHT410 User Guide M211737EN-H
7.4 Serial line output and communication commands.....................................52
7.4.1 Measurement output commands.......................................................... 52
7.4.2 Measurement output format commands.............................................56
7.4.3 Serial line communication commands..................................................59
7.5 Analog output commands............................................................................ 63
7.6 Calibration and adjustment commands.......................................................67
7.7 Other commands............................................................................................68
8. DNP3 protocol.................................................................................................71
8.1 Taking DNP3 protocol into use...................................................................... 71
9. Vaisala MI70 Handheld Indicator........................................................... 73
9.1 MI70 indicator overview................................................................................ 73
9.1.1 MI70 indicator parts................................................................................73
9.1.2 Basic display.............................................................................................74
9.1.3 Graphical display..................................................................................... 74
9.1.4 Main menu................................................................................................ 75
9.2 Installing and recharging MI70 batteries..................................................... 75
9.3 Connecting MI70 to service port.................................................................. 76
9.4 Holding and saving the display.....................................................................76
9.5 Recording data................................................................................................77
9.5.1 Starting and stopping the recording.....................................................77
9.5.2 Viewing recorded data........................................................................... 78
9.5.3 Clearing data memory............................................................................78
9.6 Comparing readings with MM70 probe.......................................................78
9.7 Changing the rechargeable battery pack....................................................79
10. Vaisala Indigo520 Transmitter................................................................. 81
10.1 Taking Indigo520 Modbus settings into use in MHT410.............................81
10.2 Cabling and cable gland................................................................................ 82
10.3 Indigo520 and MHT410 wiring diagram......................................................83
10.4 MHT410 status messages shown in Indigo520...........................................84
10.5 Settings in Indigo520.....................................................................................84
11. Calibration and adjustment......................................................................85
11.1 H2 calibration and adjustment......................................................................85
11.1.1 Taking DGA sample and saving current H2 reading............................85
11.1.2 Entering DGA H2 reading to transmitter.............................................. 87
11.1.3 Clearing H2 calibration and adjustment............................................... 88
11.2 RS & T calibration and adjustment...............................................................89
12. Troubleshooting............................................................................................. 91
12.1 Error states.......................................................................................................91
12.2 Changing bleed screw................................................................................... 92
13. Technical data................................................................................................ 93
13.1 MHT410 specifications................................................................................... 93
13.2 Spare parts and accessories..........................................................................97
2
Table of contents
13.3 Dimensions...................................................................................................... 98
13.4 Wiring diagrams.............................................................................................99
13.5 Recycling.........................................................................................................101
Appendix A: Operating principle..............................................................104
A.1 Method used for measuring moisture in oil...............................................105
A.2 Transformer oil..............................................................................................105
Appendix B: Modbus reference.................................................................107
B.1 Default Modbus communication settings..................................................107
B.2 Function codes..............................................................................................107
B.3 Data encoding............................................................................................... 107
B.3.1 32-bit floating point or 32-bit integer format....................................108
B.3.2 16-bit integer format.............................................................................108
B.4 Register map.................................................................................................108
B.5 Modbus registers.......................................................................................... 109
B.5.1 Measurement data registers................................................................ 109
B.5.2 Status registers........................................................................................ 111
B.6 Device identification objects........................................................................ 112
B.7 Exception responses......................................................................................112
Appendix C:
Moisture ppmw calculation for transformer oils.............113
C.1 Calculation model with average coecients..............................................113
C.2 Calculation model with oil-specific coecients.........................................113
Maintenance and calibration services........................................................115
Technical support........................................................................................... 115
Warranty........................................................................................................... 115
3
MHT410 User Guide M211737EN-H
List of figures
Figure 1 MHT410 order code example (first digit 1 = mineral oil)........................ 16
Figure 2 Recommended installation locations.........................................................20
Figure 3 Loop-powered display 242003....................................................................32
Figure 4 Analog output overrange behavior............................................................ 38
Figure 5 Analog output overrange behavior............................................................64
Figure 6 MI70 indicator parts........................................................................................ 73
Figure 7 MI70 basic display............................................................................................74
Figure 8 Example of MI70 display with MHT410 in port I and
MM70 probe in port II. Shown parameters: aw (I), aw (II), Δ aw........ 79
Figure 9 Wiring between Indigo520 and MHT410 screw terminals....................83
Figure 10 MHT410 transmitter dimensions..................................................................98
Figure 11 Wiring Option 1: Wiring with four power supplies.
Separate loop-powering and galvanic isolation for
analog outputs. In transmitters ordered with Vaisala
cable CBL210392-5M, the cable is pre-wired according
to this option.....................................................................................................99
Figure 12 Wiring Option 2: Wiring with two power supplies.
Common loop-powering and galvanic isolation for
analog outputs............................................................................................... 100
Figure 13 Wiring Option 3: Wiring with one power supply. Non-
isolated configuration for analog outputs sharing
transmitter power supply............................................................................ 100
Figure 14 Wiring Option 4: Wiring with one power supply.
Alternative wiring to option 3, providing reduced
current loop area for analog outputs........................................................ 101
Figure 15 Materials for recycling...................................................................................102
Figure 16 Measuring hydrogen and moisture in oil with MHT410....................... 104
Figure 17 Water solubility of transformer oils versus temperature.
The margins show the range of variation of water
solubility found in mineral oils....................................................................106
4
List of tables
Table 1 Document versions (English)...........................................................................9
Table 2 Related manuals.................................................................................................. 9
Table 3 Analog output values in dierent transmitter statuses..........................37
Table 4 Default serial interface settings....................................................................40
Table 5 Service port serial interface settings...........................................................43
Table 6 Serial commands.............................................................................................. 44
Table 7 ? command.........................................................................................................46
Table 8 alarm command................................................................................................ 47
Table 9 errlog command............................................................................................... 48
Table 10 errs command....................................................................................................49
Table 11 help command...................................................................................................50
Table 12 system command............................................................................................. 50
Table 13 time command....................................................................................................51
Table 14 vers command.................................................................................................... 51
Table 15 intv command.................................................................................................... 52
Table 16 log command..................................................................................................... 52
Table 17 r command..........................................................................................................55
Table 18 send command.................................................................................................. 55
Table 19 form command.................................................................................................. 56
Table 20 Output parameters for form command...................................................... 57
Table 21 Modifiers for form command.........................................................................58
Table 22 unit command....................................................................................................59
Table 23 addr command.................................................................................................. 59
Table 24 close command.................................................................................................60
Table 25 open command................................................................................................. 60
Table 26 sdelay command.............................................................................................. 60
Table 27 seri command..................................................................................................... 61
Table 28 smode command.............................................................................................. 62
Table 29 aerr command................................................................................................... 63
Table 30 aover command.................................................................................................63
Table 31 asel command................................................................................................... 64
Table 32 atest command..................................................................................................66
Table 33 cdate command.................................................................................................67
Table 34 ctext command..................................................................................................67
Table 35 h2 da and h2 db commands.......................................................................... 68
Table 36 h2 x command................................................................................................... 68
Table 37 dnp3 addr command....................................................................................... 68
Table 38 filt command...................................................................................................... 69
Table 39 frestore command............................................................................................69
Table 40 reset command..................................................................................................70
Table 41 oil command...................................................................................................... 70
Table 42 h2 is command.................................................................................................. 70
Table 43 Default communication settings....................................................................71
Table 44 MHT410 communication settings for Indigo520.......................................81
Table 45 MHT410 status messages shown in Indigo520.........................................84
List of tables
5
MHT410 User Guide M211737EN-H
Table 46 Possible error messages via Vaisala Industrial Protocol.........................91
Table 47 MHT410 measurement performance...........................................................93
Table 48 MHT410 operating environment...................................................................94
Table 49 MHT410 inputs and outputs...........................................................................94
Table 50 MHT410 mechanical specifications.............................................................. 95
Table 51 MHT410 compliance.........................................................................................96
Table 52 Display with relays (external option).......................................................... 96
Table 53 MHT410 spare parts and accessories.......................................................... 97
Table 54 Vaisala cable CBL210392-5M wire colors (when pre-wired)................99
Table 55 Materials for recycling....................................................................................103
Table 56 Optimal sensor positions.............................................................................. 104
Table 57 Default Modbus RTU communication settings....................................... 107
Table 58 Supported Modbus function codes............................................................107
Table 59 Interpretation of 16-bit signed integer values.........................................108
Table 60 Modbus register blocks................................................................................. 109
Table 61 Modbus measurement data registers (read-only).................................109
Table 62 Modbus status registers (read-only)............................................................111
Table 63 Modbus device status bits.............................................................................. 111
Table 64 Device identification objects.........................................................................112
Table 65 Modbus exception responses........................................................................112
6
Chapter 1 – Safety
1. Safety
Vaisala Moisture, Hydrogen and Temperature Transmitter MHT410 for Transformer Oil delivered
to you has been tested for safety and approved as shipped from the factory. Note the
following precautions:
CAUTION!
before installing the product.
WARNING!
to minimize shock hazard.
DANGER!
Pay attention to transmitter installation depth and possible energized parts
inside the power transformer to minimize electric shock hazard and equipment
damage.
CAUTION!
documentation. Improper modification or use may lead to safety hazards,
equipment damage, failure to perform according to specification, or decreased
equipment lifetime.
CAUTION!
installed. The probe body goes through the valve into the oil flow, and trying to
close the valve will damage the probe body and/or the valve.
If you must close the ball valve while the transmitter is on the valve, first open
the small tightening nut and pull the probe body out as far as possible. Then
close the valve.
Read the Quick Guide (including installation instructions) carefully
Ground the product and verify installation grounding periodically
Severe risk of death and of damage to transformer:
Do not modify the unit or use it in ways not described in the
Do not try to close the ball valve when the transmitter is fully
CAUTION!
step on the transmitter when the transmitter is installed.
CAUTION!
installation site.
To avoid damage to the installation valve of the transformer, do not
Follow the safety regulations related to the application and
7
MHT410 User Guide M211737EN-H
1.1 ESD protection
Electrostatic Discharge (ESD) can damage electronic circuits. Vaisala products are adequately
protected against ESD for their intended use. However, it is possible to damage the product by
delivering electrostatic discharges when touching, removing, or inserting any objects in the
equipment housing.
To avoid delivering high static voltages to the product:
• Handle ESD‑sensitive components on a properly grounded and protected ESD workbench
or by grounding yourself to the equipment chassis with a wrist strap and a resistive
connection cord.
• If you are unable to take either precaution, touch a conductive part of the equipment
chassis with your other hand before touching ESD‑sensitive components.
• Hold component boards by the edges and avoid touching component contacts.
8
Chapter 2 – About this document
2. About this document
Table 1 Document versions (English)
Document code Date Description
M211737EN-H March 2021 This document.
New chapters:
• Vaisala Indigo520 Transmitter (page 81)
• Clearing H2 calibration and adjustment (page 88)
Updated content:
• Added silicone oil to the list of supported oils
• Serial commands summary (page 44)
• Calibration and adjustment commands (page 67)
• Error states (page 91)
• MHT410
• Status registers (page 111)
M211737EN-G November 2018 Previous version. Added natural and synthetic ester oil
support information and instructions on checking the oil
type set at the factory from the product label. Added
instructions on
calculation coecients. Clarified the information on the
temperature range for accurate measurement in hydrogen
and temperature accuracy specifications and added
sensor head temperature tolerance specification. Added
instructions on using a safety pin with a warning label to
lock the valve handle in open position after installation.
M211737EN-F May 2018 Updated installation instructions regarding PTFE tape and
installation depth. Added DNP3 protocol information.
Added clarification about using the RS-485 line of the
screw terminals with Modbus or Vaisala Industrial Protocol.
Added maximum power consumption specification.
Added new parameter options for analog outputs: daily,
weekly, and monthly ROC and 24-hour average for H2 and
H2O. Added
change (ROC) readings. Changed unit "ppm" to "ppmv"
for H2 and to "ppmw" for H2O.
specifications (page 93)
configuring oil-specific moisture in oil
clarification about the calculation of rate of
Table 2 Related manuals
Document code Description
M211736EN Vaisala MHT410 Quick Guide
M212287EN Vaisala Indigo520 User Guide
M211784EN Loop-Powered Display 242003 for MHT410 Technical Note
9
MHT410 User Guide M211737EN-H
2.1 Documentation conventions
WARNING!
follow instructions carefully at this point, there is a risk of injury or even death.
CAUTION!
follow instructions carefully at this point, the product could be damaged or
important data could be lost.
Note highlights important information on using the product.
Tip gives information for using the product more eciently.
Lists tools needed to perform the task.
Indicates that you need to take some notes during the task.
Warning alerts you to a serious hazard. If you do not read and
Caution warns you of a potential hazard. If you do not read and
2.2 Regulatory statements
2.2.1 FCC Part 15 compliance statement
This equipment has been tested and found to comply with the limits for a Class A digital
device, pursuant to part 15 of the FCC Rules. These limits are designed to provide reasonable
protection against harmful interference when the equipment is operated in a commercial
environment. This equipment generates, uses, and can radiate radio frequency energy and, if
not installed and used in accordance with the instruction manual, may cause harmful
interference to radio communications. Operation of this equipment in a residential area is likely
to cause harmful interference in which case the user will be required to correct the interference
at his own expense.
10
Chapter 2 – About this document
CAUTION!
by the party responsible for compliance could void the user's authority to
operate the equipment.
This device complies with part 15 of the FCC Rules. Operation is subject to the
following two conditions: (1) This device may not cause harmful interference, and
(2) this device must accept any interference received, including interference that
may cause undesired operation.
Changes or modifications to this equipment not expressly approved
2.3 Trademarks
HUMICAPâ is a registered trademark of Vaisala Oyj.
Modbusâ is a registered trademark of Schneider Automation Inc.
All other product or company names that may be mentioned in this publication are trade
names, trademarks, or registered trademarks of their respective owners.
11
MHT410 User Guide M211737EN-H
3. Product overview
Vaisala Moisture, Hydrogen and Temperature Transmitter MHT410 for Transformer Oil is
designed for online monitoring of insulating oil in power transformers. The transmitter
provides an accurate real-time measurement result of moisture, hydrogen and temperature
measured in oil, enabling reliable conclusions on the transformer's condition without delay.
The transmitter provides digital and analog outputs of all the measured parameters.
3.1 Main features
• Reliable online measurement of transformer oil for the following parameters:
• Moisture: relative saturation (%RS), water activity, and water content (ppmw)
• Hydrogen concentration (ppmv in oil)
• Temperature (°C and °F)
• Compatible with mineral oils, natural ester oils, synthetic ester oils, and silicone oils
• No need to take oil samples for measurement
• Installable and retro-fittable on a ball valve (ball valve thread: female 1.5" NPT)
• Low maintenance requirements due to excellent long term stability
• Outputs
• Digital: Modbus, DNP3, and Vaisala industrial protocol over RS-485
• Analog: three channels with scalable current output
• Status indication LEDs in the front panel
• Built-in data logging
• USB connectivity for service connections using an optional USB M8 cable
• Display options:
• Loop-powered display for continuous use
• MI70 handheld meter for temporary use
• Compatible with Vaisala Indigo500 series transmitters
More information
‣
Oil types (page 16)
‣
Status LEDs (page 17)
‣
Data logging (page 17)
‣
Connecting to MHT410 via service port (page 41)
‣
Loop-powered display (page 31)
‣
Vaisala MI70 Handheld Indicator (page 73)
‣
Technical data (page 93)
12
59876
123
4
10
Chapter 3 – Product overview
3.2 Product parts and package contents
13
5 mm
3 mm
111413
12
+
MHT410 User Guide M211737EN-H
No. Item
1 = Electronics housing.
The front cover is additionally connected to the housing with a grounding wire.
2 = Weather shield
3 = Bleed screw
4 = Probe body
5 = Small tightening nut, used to adjust and fix the depth of the transmitter in the valve.
You can move the tightening nut and the mounting nut along the probe body.
6 = Mounting nut, used to fasten the transmitter in the ball valve.
You can move the tightening nut and the mounting nut along the probe body.
7 = Hydrogen sensor
8 = Moisture and temperature sensors under the filter
9 = Product label
10 = Lead-throughs (2 pcs) with a minimum of one cable gland (size M20x1.5) or conduit
Installation Kit:
11 = PTFE tape roll
12 = Allen keys (3 mm and 5 mm)
13 = Extra bleed screw and sealing ring
14 = Extra terminal blocks (4 x 4 screw terminals)
fitting.
Unused lead-throughs are plugged.
More information
‣
Dimensions (page 98)
14
Chapter 3 – Product overview
3.3 Measurement parameters and units
Parameter Abbreviation Unit
H2 concentration in oil
• 1 h average
• 24 h average
Rate of change of H2 concentration
In a day Daily ROC ppmv/day
In a week Weekly ROC ppmv/week
In a month Monthly ROC ppmv/month
Moisture in oil
Relative saturation RS %RS
Water activity aw (=RS/100) (no unit)
H2O concentration in oil
(current)
H2O concentration in oil (24 h
average)
Rate of change of H2O concentration in oil
In a day Daily ROC ppmw/day
In a week Weekly ROC ppmw/week
In a month Monthly ROC ppmw/month
Temperature
Oil temperature T °C or °F
H2 ppm
H2O ppm
H2O ppm
v
w
w
The rate of change (ROC) for H2 and for H2O shows the dierence in ppm between the latest
24-hour average and the 24-hour average 1 day ago (daily ROC), 7 days ago (weekly ROC), or
30 days ago (monthly ROC). ROC readings are updated every 12 hours.
After starting up or resetting the transmitter, ROC readings are available as follows:
• Daily ROC: after 2 days
• Weekly ROC: after 8 days
• Monthly ROC: after 31 days
Before the ROC readings are available, the ROC measurement registers in digital outputs
contain a "NaN" value, and the ROC analog outputs are set to 3.0 mA (= measurement not
ready).
15
MHT410 1 B E G 0
1
MHT410 User Guide M211737EN-H
3.4 Oil types
MHT410 is compatible with the following oil types:
• Mineral oils
• Natural ester oils
• Synthetic ester oils
• Silicone oil
CAUTION!
for the unit at the factory. Using the transmitter with a dierent oil type requires
sending the unit to Vaisala for reconfiguration.
The oil type that MHT410 measures (mineral oils, natural ester oils, synthetic ester oils, or
silicone oil) is selected when ordering the transmitter. For instructions on checking the oil type
set at the factory from the product label, see Oil type information in order code (page 16).
Never use MHT410 with any other oil type than the one configured
3.4.1 Oil type information in order code
MHT410 has been configured for a specific oil type based on the selection made when
ordering the transmitter, and must not be used with other oil types. The oil type configuration
set at the factory can be checked from the first digit (1, 2, 3, or 4) of the order code in the
MHT410 product label.
Figure 1 MHT410 order code example (first digit 1 = mineral oil)
First digit of the order code. The oil type configuration is shown in the first digit as 1, 2, 3,
1
or 4:
• 1 = Mineral oils (shown)
• 2 = Natural ester oils
• 3 = Synthetic ester oils
• 4 = Silicone oils
3.4.2 Oil-specific coecients for ppmw moisture measurement
MHT410 can be ordered with ppmw moisture output (average mass concentration of water in
oil). The calculation model that MHT410 uses for ppmw measurement is based on the average
water solubility behavior of transformer oils (see Calculation model with average coecients
(page 113)). If additional accuracy is required, you can configure oil-specific coecients into
MHT410 using Vaisala Industrial Protocol serial commands (see Table 41 (page 70)), or contact
Vaisala about setting the coecients.
16
Chapter 3 – Product overview
More information
‣
Moisture ppmw calculation for transformer oils (page 113)
‣
Other commands (page 68)
3.5 Data logging
The transmitter automatically saves the measurement readings and other events in a log every
12 hours (configurable interval). The log can contain approximately 32000 entries.
The following events are logged:
• Hydrogen (ppmv) reading as 1 h average or 24 h average
• Moisture in oil (%RS and ppmw) and temperature (°C) readings as instant values or 24 h
averages
• Power outages
• Short power outages that don't turn o transmitter power (flagged "UPS")
• Long power outages that turn o transmitter power (flagged first as "UPS" and then
as "Reset")
• Manual resets (flagged as "Reset")
• Uptime and total operating time
• Occasions of exceeding hydrogen alarm level (optional)
To view the log and change the logging settings, use Vaisala Industrial Protocol.
You can save the log as a file from PuTTY by configuring the following settings in
PuTTY before opening the connection:
In the Session > Logging view:
• Session logging: Select "Printable output".
• Log file name: Type a name for the log file (use the file extension .txt) and
browse to the save location.
To prevent the log from getting very long, consider saving and then clearing the
log every few years.
More information
‣
Vaisala Industrial Protocol (page 40)
‣
Measurement output commands (page 52)
3.6
Status LEDs
When the transmitter is ON, one of the LEDs is always illuminated (solid or blinking). If no LED
is illuminated, the transmitter is OFF.
17
Wait...
OK
Alarm
Error
MHT410 User Guide M211737EN-H
LED color and text Description
Green, blinking:
Transmitter is preparing H2 measurement after start-up or reset.
Green, solid:
Red, blinking:
Red, solid:
Transmitter is measuring.
H2 concentration is above the alarm limit.
Transmitter is in error state.
18
4. Installation
Before you install the transmitter:
• Go through the check list in section Planning the installation (page 19).
• Read this whole guide carefully.
Chapter 4 – Installation
CAUTION!
configured for MHT410. See Oil type information in order code (page 16).
The installation instructions in this section are the same as in the MHT410 Quick
Guide.
Make sure the oil type of the transformer matches the oil type
4.1 Planning the installation
• Choose the installation location on the transformer (see Recommended installation
locations (page 20)).
CAUTION!
from the valve specifications. The correct thread of the valve is female 1.5"
NPT. Do not install the transmitter in a valve with a dierent thread. For
example, the R thread is incorrect. If you use a dierent thread than female
1.5" NPT, your equipment may be damaged and the connection is not leak
tight. If you are not sure which thread your installation valve has, verify the
thread with a 1.5" NPT thread gauge.
• Make sure the oil type of the transformer matches the one configured for MHT410
(mineral oil, natural ester oil, synthetic ester oil, or silicone oil).
• Make sure you have all the required tools for installing the transmitter. The required tools
are presented in the installation instructions.
• Choose the output signals: analog and/or digital.
• Choose the electrical wiring option. If the transmitter was ordered with the Vaisala cable
CBL210392-5M, the cable is already pre-connected to the transmitter according to Wiring
Option 1.
Make sure the installation valve and threads are appropriate
More information
‣
Wiring diagrams (page 99)
19
MHT410 User Guide M211737EN-H
4.1.1 Recommended installation locations
The probe must always be installed in a valve. The correct thread of the valve is female 1.5"
NPT. Do not install the transmitter in a valve with a dierent thread. For example, the R thread
is incorrect. If you use a dierent thread than female 1.5" NPT, your equipment may be
damaged and the connection is not leak tight.
Figure 2 Recommended installation locations
Recommendation
Recommended:
Straight section in the
radiator’s outlet pipe.
20
Description
This is the best location for the transmitter.
The oil is measured in flow, which makes the oil sample
representative and instant. This is essential especially for correct
oil moisture measurement.
Compared to the radiator inlet pipe, oil in the outlet pipe is
cooled, preventing unnecessary heating of the sensors and the
transmitter.
Recommendation Description
Possible alternative:
Wall of the oil tank, high
enough from the bottom to
enable proper oil movement.
An instrumentation valve is recommended. This is a typical valve
that is meant for oil analysis.
Moisture response time is moderate depending on the oil volume
and transmitter installation.
DANGER!
damage to transformer:
Pay attention to transmitter installation depth
and possible energized parts inside the power
transformer to minimize electric shock hazard
and equipment damage.
The moisture response can be poor due to static oil flow. There is
also a risk of separated water (leading to wrong results) and oil
Not recommended:
Drain valve of the oil tank.
sludge (risk of sensor contamination and clogged filters).
4.2 Mechanical installation
Chapter 4 – Installation
Severe risk of death and of
CAUTION!
Before you install the transmitter:
• Make sure there is no negative pressure in the transformer. If there is negative
pressure when you open the bleed screw during installation, air will flow into
the transformer oil tank.
• Do not open the ball valve on the transformer until you are instructed to do so
in this guide.
• Make sure the bleed screw on the mounting nut is closed.
• 2 wrenches (50 mm and 36 mm)
• Allen key (3 mm, provided)
• PTFE tape (provided)
• Gloves
• Bucket and cloth
21
MHT410 User Guide M211737EN-H
1. Remove the protective cap with sorbent packet from the mounting nut.
In case of rain, do not let any water fall on the filter.
22
PTFE
Chapter 4 – Installation
2. Apply PTFE tape tightly on the mounting nut threads.
a. Before you start, clean the threads with a cloth.
b. To make sure you wrap the tape in the correct direction, hold the transmitter so that
the product label is facing you and the mounting nut points away from you.
c. Start wrapping counter-clockwise from the second thread on the tip of the mounting
nut.
d. Wrap each round very tightly about half way on top of the previous round so that the
tape overlaps. Stretch the tape for optimal tightness. Apply a couple of rounds of
tape.
23
OPEN
max. 3 × 360°
MHT410 User Guide M211737EN-H
3. Make sure the bleed screw is closed. Fasten the mounting nut on the ball valve to finger-
tightness with your hand. Leave the bleed screw directly on top of the nut.
If you cannot position the bleed screw on top of the mounting nut by tightening just with
your hand, you can use a wrench (50 mm) to turn the mounting nut a maximum of a ½
turn.
CAUTION!
fastened it on the valve, you must remove the transmitter from the valve,
remove the PTFE tape, and start again from step 2 with new PTFE tape.
4. With a 3 mm Allen key, loosen the bleed screw. Place a bucket under the mounting nut.
If you need to loosen the mounting nut after you have
24
CLOSE
SLOW
Chapter 4 – Installation
5. Start opening the valve very carefully to let air out through the bleed screw.
CAUTION!
If you open the valve too quickly, the air inside the mounting
nut will flow into the transformer instead.
When oil flows out, close the bleed screw. Clean the area with a cloth and open the ball
valve fully.
6. Continue tightening the mounting nut with a wrench. Be very careful not to over-tighten
the connection. Approximately 5 ... 8 mm of the mounting nut threads remain outside the
valve.
If the connection leaks after you have tightened the mounting nut, check the
thread type of the installation valve.
• If the valve thread is other than female 1.5" NPT (incorrect), do not
install the transmitter in that valve.
• If the valve thread is female 1.5" NPT (correct), close the valve, open
the mounting nut and remove the transmitter, remove old PTFE tape
and apply a thicker layer of new PTFE tape. Then continue from
step 3.
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180 ... 190 mm
200 mm
MHT410 User Guide M211737EN-H
7. Push the probe to the correct depth. The correct depth depends on where the installation
valve is located: radiator pipe or transformer wall.
• Valve in radiator pipe: Install the probe so that the back of the weather shield is
180 ... 190 mm from the pipe surface.
• Valve in transformer wall: Install the probe so that the back of the weather shield is
200 mm from the transformer wall.
DANGER!
Severe risk of death and of damage to transformer:
Pay attention to transmitter installation depth and possible energized
parts inside the power transformer to minimize electric shock hazard
and equipment damage.
When the probe is in the correct depth, turn the transmitter 90 degrees two to three
times to remove any air bubbles from the sensor area.
26
DO NOT CLOSE VALVE
WHEN TRANSMITTER
IS INSTALLED!
HOW TO CLOSE VALVE:
1
2
3
DO NOT CLOSE VALVE
WHEN TRANSMITTER
IS INSTALLED!
HOW TO CLOSE VALVE:
1
2
3
PULL INSTRUMENT OUT
BEFORE CLOSING VALVE
Chapter 4 – Installation
8. Tighten the small tightening nut with a wrench until the probe is securely fastened.
9. Press the caution sticker on the MHT410 weather shield or other visible location nearby,
and lock the handle of the valve in the open position with the safety pin.
More information
‣
Dimensions (page 98)
27
+
CH2
– CH2
+
CH1
– CH1
SHLD
SHLD
RS
GND
D –
D
+
+
Vs
– Vs
3 4 5 6 7 8
9
10 11 12 13 14 15 16
RS-485
NALOG OUTPUTS
SERVICE
PORT
19200 b/s, 8, n, 1
POWER
SERIAL COMMANDS
Device information ?
List of errors ERRS
List of commands HELP
Modbus default
address: 240
RS-485
TERMINATION
ON
OFF
See manual for further
commands.
www.vaisala.com/MHT410
MHT410 User Guide M211737EN-H
4.3 Electrical installation
When connecting MHT410 to the Indigo520 transmitter, see also Indigo520 and
MHT410 wiring diagram (page 83).
If MHT410 was ordered with the Vaisala cable CBL210392-5M, the cable is already
pre-connected to MHT410 according to Wiring Option 1.
If cable is not pre-wired:
• Allen key (5 mm, provided)
• 2 medium wrenches (24 mm)
• Flat head screwdriver (2.5 mm)
• Wire-cutting pliers
• Suitable cable. You can order the following cables from Vaisala:
• 5 m shielded PUR cable (order code: CBL210392-5MSP)
• 10 m shielded PUR cable (order code: CBL210392-10MSP)
1. Open the electronics housing with a 5 mm Allen key to access the screw terminals.
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