MMT330 - Temperature and humidity sensor VAISALA - Free user manual and instructions

Product type	Humidity and temperature transmitter for oil
Brand	VAISALA
Model	MMT330
Category	Temperature and humidity measurement probe
Power supply	24 VAC (optional power supply module for 100-240 VAC)
Display	With screen (optional)
Analog outputs	4-20 mA (configurable via DIP switches)
Serial communication	RS-232 (service port), RS-485 (optional module)
Sensor	Vaisala HUMICAP® for humidity in oil
Humidity measurement range	0 ... 1 aw (water activity)
Operating temperature range	-40 °C ... +80 °C
Dimensions (enclosure)	Approximately 200 x 150 x 100 mm (standard)
Weight	Approximately 1 kg
Mounting	Wall mounting (4 M6 screws not supplied)
Enclosure material	Robust plastic
Protection rating	IP65 (estimated)
Available languages	French, English, German, Spanish, Finnish, Japanese, Dutch, Swedish, Chinese
Calibration	Factory calibrated; recalibration possible by user or at service center
Maintenance and cleaning	Clean the exterior with a soft, dry cloth; avoid solvents
Safety	Electrical connection by a certified electrician for the mains module; do not connect the same wire to + and - of two transmitters
Spare parts and repairability	Optional modules (relay, RS-485, power supply); repair by Vaisala Service Centers
General information	Quick start guide included; full user manual available online

Frequently Asked Questions - MMT330 VAISALA

How to install the MMT330 probe in an oil tank?

Choose a representative location in the oil circuit (e.g., a high-flow supply line). Avoid tank bottoms, bends where water can accumulate, and turbulent areas. Fasten the transmitter enclosure to the wall with 4 M6 screws (not supplied). Mount the sensor head horizontally or vertically to prevent condensate from dripping onto the sensor.

What is the required power supply?

The standard power supply is 24 VAC. An optional power supply module allows a 100-240 VAC mains connection. Use a separate floating power supply for each transmitter if using 24 VAC. Mains connection must be performed by a certified electrician.

How to wire the transmitter?

Use a shielded electrical cable with 3 to 10 wires, diameter 8-11 mm. Connect the power supply and signals to the screw terminals. Properly ground the cable shield following the procedure illustrated in the manual: strip, fold back the braid 90°, insert the contact socket, and tighten the nut.

How to configure the analog outputs?

The DIP switches inside the transmitter allow setting the analog outputs (4-20 mA). Consult the user guide for exact settings. The RS-232 service port can be used for further configuration.

What to do if the display comes on in a foreign language?

At first power-up, the language selection menu appears. Use the arrow keys to choose the desired language and press SELECT. If the language has already been set, you can change it via the main menu (see manual).

How to interpret humidity measurements in oil?

The transmitter measures water activity (aw) from 0 to 1. This value depends on the pressure and temperature of the process. For accurate calculations, ensure that the pressure at the sensor matches the actual process pressure. Temperature is only critical if it falls below the dew point.

What is the calibration procedure?

The transmitter is factory calibrated. Recalibrate if you suspect drift. Calibration can be performed by a Vaisala service center or by the user with appropriate equipment. Consult the manual for detailed instructions.

How to maintain the transmitter?

Clean the exterior of the enclosure with a soft, dry cloth. Do not use solvents. Periodically check the condition of the cable and connections. In case of malfunction, contact a Vaisala service center.

Can I use multiple transmitters on the same power supply?

No, each transmitter must have its own floating 24 VAC power supply. Never connect the same wire to the + of one transmitter and the - of another, as this would cause a transformer short circuit.

Where to find the contact information of service centers?

North America: [phone]. Europe: [phone]. Tokyo: [phone]. Beijing: [phone]. More information at www.vaisala.com.

USER MANUAL MMT330 VAISALA

This Quick Guide provides an overview on how to install Vaisala HUMICAP® Humidity and Temperature Transmitter Series HMT330, Vaisala DRYCAP® Dewpoint and Temperature Transmitter Series DMT340 and Vaisala HUMICAP® Moisture and Temperature Transmitter Series for Oil MMT330. Please refer to the relevant User's Guides for detailed information on the use of the products.

Things to Consider

When Measuring Dewpoint

• If a sampling system is built instead of direct probe installation, it is important that the system is leak-proof. Recommended material for sampling system construction is stainless steel. Also PTFE may be used down to dewpoints of -40^ / -40^ .

• Dewpoint is a pressure dependent parameter. It is important that the pressure at the sensor is the true process pressure. The temperature is not of major importance, as long as it is above the process dewpoint in order to avoid condensation.

When Measuring Relative Humidity

In humidity measurement it is essential that the temperature of the probe and the measured gas is the same. Even a small

difference in temperature between the environment and the probe can cause an error of several percentages in RH.

Mounting the Probes with Cable

Mount the probes with a cable with the sensor head horizontally or vertically. This way, any water condensing on the tube cannot flow onto the sensor.

When installing probe into a chamber with a higher T than the surrounding the point of entry must always be carefully insulated. The cable must also be allowed to hang loosely as this prevents any condensed water from running onto the sensor head along the cable.

Figure 1 Horizontal Mounting of Sensor Head

Numbers refer to Figure 1 above.

1 = To be sealed.
2 = To be insulated.
3 = Insulate the cable.
4 = Let the cable hang loosely. This prevents condensed water running to the sensor along the cable.

• Refer to the appropriate User's Guides for further installation instructions for probes with a cable as well as other installation possibilities.

When Measuring Moisture in Oil

• The measurement should be done in a location that provides a representative sample of your entire oil system (for example, a high flow feed line or return line to reservoir). The sensor reads that which it is in contact with only.

• Locations to avoid include the bottom of oil reservoirs and bends in a pipeline where free water may settle out as well as areas where heavy air bubbling could occur due to turbulence caused by pumps or agitators.

Transmitter Housing Standard Installation

Mount the housing by fastening the transmitter to the wall with 4 screws, for example M6 (not provided). Refer to the User's Guides for the use of the optional mounting plates.

Figure 2 Standard Mounting Dimensions (in mm/inch)

Operation

Figure 3 Inside of the Open Transmitter

Numbers refer to Figure 3 above.

1 = Service port (RS-232)  
2 = Dip switches for analog output settings  
3 = Power supply and signal wiring screw terminals  
4 = Relay/RS-485 module (optional)  
5 = Grounding connector  
6 = Power supply module (optional)  
7 = Relay module/third analog output module (optional)  
8 = Probe  
9 = Output isolation module/DC-DC converter (optional)  
10 = Adjustment buttons with indicator led 

Wiring

• A single electrical cable with a screen and three to ten wires is recommended for power and analog/serial connections. The cable diameter should be 8 11 ~mm . The number of cable bushings depends on the transmitter options. Ground the screen of the electrical cable properly to achieve the best possible EMC performance.

Fig. 1

Fig. 2

Fig. 3
Figure 4 Grounding the Screen of Electrical Cable

a. Cut back outer sheath to desired length.
b. Cut back screen braiding or screen foil to dimension X (see figure 2).
c. Push the domed cap nut (item 1) and the seal insert with contact socket of the gland (item 2 + 3 ) onto the cable as shown in the diagram.
d. Bend over the screen braiding or screen foil by about 90^ (item 4).
e. Push the seal insert with the contact socket of the gland (item 2+3) up to the screen braiding or screen foil.
f. Mount lower part (item 5) on the housing.
g. Push the seal with the contact socket of the gland and (item 2+3) flush into the lower part (item 5).
h. Screw the domed cap nut (item 1) onto the lower part (item 5).

When connecting to a 24 VAC power supply a separate floating supply for each transmitter is recommended.

WARNING

The AC (mains) power connection may be connected to the power supply module only by an authorized electrician.

WARNING

Make sure that you connect only unpowered wires.

CAUTION

In case you have only one AC supply, never connect same wire to the + connector of a transmitter and to the - connector of another one. This will short-circuit the transformer.

Starting Operation

• Within a few seconds after power-up the led on the cover of the transmitter is lit continuously indicating normal operation. When the transmitter equipped with a display is turned on the first time, the language selection window opens.
• Select the language with arrow buttons and press the SELECT button.

Figure 5 Language Selection Menu

• The pressure has an effect on humidity calculations and accuracy. Therefore, accurate calculations can be achieved only when the process pressure is taken into account.
• In DMT340, the start-up time is about 6 minutes due to a self-diagnostics procedure. During this, the outputs are frozen.

Maintenance

• The transmitter is fully calibrated and adjusted as shipped from factory.

• Calibration must be done always when there is a reason to believe that the device is not within the accuracy specifications. Calibration and adjustment can be carried out in Vaisala Service Centers or by the user

NORTH AMERICAN SERVICE CENTER,

phone: [phone]

EUROPEAN SERVICE CENTER,

phone: [phone]

TOKYO SERVICE CENTER,

phone: [phone]

BEIJING SERVICE CENTER ,

phone: [phone]

www.vaisala.com