Endress+Hauser Deltabar PMD78B - Page 13

Deltabar PMD78B HART Electrical connection
Endress+Hauser 13
6.2.4 4-20 mA HART
2
3
4
Y
+ +
- -
I
1
mA
A0028908
 1 Block diagram of HART connection
1 Device with HART communication
2 HART communication resistor
3 Power supply
4 multimeter
The HART communication resistor of 250 Ω in the signal line is always necessary in the
case of a low-impedance power supply.
Take the voltage drop into consideration:
Maximum 6 V for a communication resistor of 250 Ω
6.2.5 Overvoltage protection
Devices without optional overvoltage protection
Equipment from Endress+Hauser fulfills the requirements of the product standard IEC / DIN
EN 61326-1 (Table 2 Industrial Environment).
Depending on the type of port (DC power supply, input/output port) different testing levels
according to IEC / DIN EN 61326-1 against transient overvoltages (Surge) are applied (IEC /
DIN EN 61000-4-5 Surge):
Test level on DC power ports and input / output ports is 1000 V line to earth
Devices with optional overvoltage protection
• Spark-over voltage: min. 400 V DC
• Tested according to IEC / DIN EN 60079-14 sub chapter 12.3 (IEC / DIN EN 60060-1
chapter 7)
• Nominal discharge current: 10 kA
Overvoltage category
Overvoltage category II