Vaisala Drycap DMT152 Guide de l'utilisateur télécharger pdf (Page 24)

User's Guide _______________________________________________________________________

22 ___________________________________________________________________ M210865EN-F

Power Supply Requirements

The DMT152 transmitters are designed to operate with a supply voltage

of 15 ... 28 VDC (voltage output version) or 21 ... 28 VDC (current

output version). When only the RS-485 output is used, 11 ... 28 VDC is

enough in typical measurement conditions.

When measuring in pressures 20 ... 50 bar

(290 ... 725 psi

) or

temperatures -40 ... 0 °C (-40 ... 32 °F), a supply voltage of 21 ... 28 VDC

is required.

The power supply should maintain the voltage for all load conditions.

The voltage fluctuations must be smaller than 0.3V, as continuous supply

voltage fluctuation may interfere with the auto-calibration function.

- If auto-calibration has failed due to the voltage fluctuation, you can

verify it using the STAT command on the serial line. See section

Show Transmitter Status on page 36.

- If auto-calibration fails repeatedly, the Autocal error code will be

activated. See section Error Codes on page 61.

Current consumption during normal operation is 20 mA. The

consumption increases during auto-calibration and sensor purge. The

maximum current consumption is 220 mA pulsed current.

NOTE

The DMT152 can be powered by the MI70 indicator or the Vaisala USB

cable. However, the power supplied by these devices may not be enough

for all functions of the transmitter (for example, the current output).

If you are using a separate power supply in connector I, connect the

power supply first before connecting the USB cable or the MI70

indicator. The order is important, since the transmitter will use the power

supply that is connected first.

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Vaisala Drycap DMT152 Guide de l'utilisateur Page 24