Pressure Sensor Conection

The pressure sensor needs a typical 24VDC power supply to power it up. In most of the digital panel meter (DPM) this power supply is built into it. Follow the below connections.

1. Connect 24VDC power supply (+) to pressure sensor (+).

2. Connect pressure sensor (-) to signal/current 4-20mA terminal (+) of DPM.

3. Connect signal/current 4-20mA terminal (-) of DPM to the 24VDC power supply (-).

This is a series connection for the 4-20mA current output to flow through the interconnected loop between the 24VDC power supply, pressure sensor and DPM.

If there is no 24VDC power supply inbuilt into the DPM, use an external power supply and follow the same interconnections as mentioned above.

If you need to introduce any other element which also requires the same 4-20mA to flow through it, break the current flow path and connect the new element in series and ensure that the polarity of the new element allows the current to flow into the (+) terminal and flow out of the (-) terminal.

Presume this answers your question.

Hi Nameaspri

I've done the above before many times and I've found that the DPM (or heat/cool controller can be used) needs to be told that 4mA = 0 and 20mA = 10 (in this case). So the DPM needs to have some programmable functions to allow for this.

To include Bar in the display, I'd be tempted to just print a Dy-mo label!

Probably the best thing would be to couple the pressure transducer to the output of a dead weight tester and obtain the 10 Bar against a calibrated gauge (or another transducer that is in test). It would depend on how accurate the OP wants it!

Hi,

What you say is correct. The DPM need to be calibrated to the required range. Here it is to be calibrated for 0 bar at 4mA and 10 bar at 20mA before it is connected into the loop.

There are 4-20mA current sources available which can be used for calibrating the DPM and then use it in the loop which has the pressure sensor (pressure transmitter). As the DPM is calibrated, it will read the 4-20mA from the pressure sensor and display the requried range which is 0 to 10 bar.

As you also mentioned the pressure sensor is to be calibrated separately with a deadweight tester or an accurate pressure source prior to connecting it into the loop.

Regards,

Thanks alot ,

I am designing a control panel for monitoring oil and water temperature for a cargo ship.The panel will be operating with 24VDC supply output from a generator.How can i protect my panel instrument from getting damaged by the high inrush current and overvoltage during generator startup. My panel instrument are design to operate with 24Vdc+/-4v.Of course for short circuit protection , i am using a fuse. One more thing is that this ship not using generator synchronizing system.

Probably best to use two UPS units in series. A fuse wouldn't be accurate or quick enough to do any good and a multimeter would only tell you anything if you happened to be looking at it at the time!

Good luck

H Kumarr68

From your dc power supply specification I would suppose that you are using the ship's dc battery system. If that is the case then you should not get any high voltages at start-up. However, if that is a serious worry for you then use a stabilised DC supply. This may help you:- http://www.mastervolt.com/view_product.php?lang=2&section=mobile&prggr_id=1014&prg_id=1084&pro_id=5218

OR http://www.alfatronix.eu/1482-dd-ddi-series-voltage-converters.php

Good luck

Chas

To confirm that the digital meter is giving the correct reading connect multimeter in the loop.

thanx.