EasyGrid LT User Guide
26
Analog output
5.3
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The EasyGrid LT 4-20mA outputs are of type 3L, non-isolated, according to ISA-50.1-1982(R1992)
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The power supplies for the 4-20mA output, is internally connected in the EasyGrid LT . Because
of that feature, only two wires are required to realise the connection to the receiver. FISO
recommends a shielded twisted pair.
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All the EasyGrid LT 4-20mA outputs negative terminals are internally connected to the power
supply ground and that ground is internally connected to the system GND at the M5 GND stud
(bottom left of the EasyGrid LT case)
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The cables shields must be grounded at only one end, we recommend to connect-them to the
EasyGrid LT M5 GND stud.
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In order to avoid ‘’ground loop’’ errors, the EasyGrid LT 4-20mA outputs shall be connected to:
floating receivers or isolated receivers or have an isolator in the loop.
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FISO recommends an input resistance of 250 ohms for the 4-20mA receivers. The maximum total
resistance of the loop (including wire resistance) should be less than 400 ohms.
