loop from an existing loop. Power is derived from the input
signal. No external power supply is required
鈥?/div>
8
Supply
8
I-AA
I-AF
V-AG
Loop powered
PRICE
INFORMATION
AND ORDERING
Wiring diagram
The voltage drop, V
d
, across the device at 20mA input is:
V
d
= 3.2 + (R
L
x 0.02)
v
4-20mA
v
V
d
v
R
L
v
v
Description
The 420I loop powered isolator is a 0(4)-20mA input, direct current isolator
powered from an existing current input loop.
Three output options are available: 4-20mA, 1-5V and the 420V which gives a 0-10V
output from a 4-20mA existing loop input, whilst dropping just 5V from the input loop.
The isolator is typically used to enable two control and instrumentation devices, e.g.
PLC and local chart recorder, with non-isolated inputs, to monitor the same
transmitter output simultaneously.
Alternatively the isolator can be used to isolate signals from non-isolated transmitters
or as a noise reduction device.
Dimensions and connections
v
63mm
Other considerations
18mm
The 420I requires a load on the output to complete the current loop. See the drawing
opposite to calculate the voltage drop V
d
, across the device.
v
58mm
Specifications
Parameter
Supply voltage
Input current
Full scale volt drop
see note
Output linearity error
Temp coefficient
Load resistance error
Time constant (10-90%)
Operating ambient
Relative humidity
Isolation voltage
Surge voltage
Mounting
Notes
Min
-50mA
Typ
Loop power
0-20mA
3.2V
Max
+50mA
3.5V
鹵0.1%
90ppm/藲C
-200nA/鈩?/div>
70藲C
90%
Comments
At 20mA input
0<R
L
<600鈩?/div>
30ms
-15藲C
0%
1kV
2.5kV for 50碌S
Transient of 10kV/碌S
Standard DIN-rail TS32/35
Absolute maximum ratings indicate sustained limits beyond which damage to the device may occur
Device is protected against reverse polarity connection
Accuracy figures based on 0-20mA input, 150鈩?load resistance, and an ambient temperature of 20藲C
Add volt drop due to load: 0.02 x R
L
e.g. 250鈩?load total volt drop = 3.5 + (0.02 x 250) = 8.5V
v
v
v
v
1 2
1.
2.
3.
4.
Output Ch +ve
Output Ch -ve
Input Ch +ve
Input Ch -ve
3 4
1
