4-20 Ma Hart; Overvoltage Protection - Endress+Hauser Liquiphant FTL64 Operating Instructions Manual

Electrical connection
22
6.3.4

4-20 mA HART

 16 Block diagram of HART connection
1 Device with HART communication
2 HART communication resistor
3 Power supply
4 Multimeter or ammeter
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 250 Ω communication resistor
6.3.5

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 supply, input/output port) different test levels
according to IEC/DIN EN 61326-1 against transient overvoltages (Surge) are applied
(IEC/DIN EN 61000-4-5): Test level on DC power ports and input/output ports is 1 000 V
line to earth
Devices with optional overvoltage protection
• Spark-over voltage: min. 400 V
• 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
Pollution degree
Pollution degree 2
1
+ +
Y
I - -
mA
DC
Liquiphant FTL64 HART
2
3
4
Endress+Hauser
A0028908