Vaisala HMT310 - Manual (Page 34)

User's Guide _______________________________________________________________________
34 ___________________________________________________________________ M210619EN-E
Power Supply Requirements
The supply voltage requirements depend on the output type, used
functionalities and pressure:
- RS-232 output (without heating and purge): 10 ... 35 VDC.
- Analog output: 15 … 35 VDC
- Heating and purge: 15 ... 35 VDC.
- Pressures above 10 bara (145 psia): minimum 24 VDC
Table 5 below lists the HMT310 current consumption for different output
types and functions.
Table 5 Current Consumption by Output Type/Function
Output/Function Consumption
RS-232 (@ 35VDC) 12 mA
Uout 10 V (10kOhm)
Channel1 & Channel 2
(@ 35VDC)
12 mA
Iout 20mA (load 511Ohm)
Channel 1 & Channel 2
(@ 35VDC)
50 mA
Purge @ 24VDC + 220 mA*
Warmed probe @ 24VDC + 240 mA*
Fuel cell @ 24VDC + 350 mA*
*maximum pulsed current
NOTE HMT310 can also be powered by an MI70 indicator or a USB cable
connection to a computer. For information on ordering the optional MI70
and USB connection cables, see section Spare Parts and Accessories on
page 93.
NOTE When the USB connection is used to power the transmitter, the heating
and purge functions may not work as intended due to the limited USB
powering capability. This depends on the computer used and
environmental conditions. Using the USB connection as a permanent
power supply is not recommended.