©2004 AUGIER SA.
I-28
I.8.9 4-20MA LOOP CURRENT :
The CCR can be delivered with two independent 4-20mA current loops with the following features :
•
The two outputs are not isolated.
•
The load to be connected must be less than 200 Ohms.
I.8.9.1 4-20mA current loop for output current and power measurements :
In the JBUS table, If bit 4 in address 98 is 0, the first output indicates the output current and the second
indicates the output power.
•
First output :
I1 = 4 mA + (Io /10A) * 16 mA.
Example: for Io = 6.6 Arms, I1 = 4 mA + (6.6/10) * 16 mA = 14.56 mA
•
Second output:
I2 = 4 mA + (Output Power/Nominal Power) * 16 mA.
Example: For 15 KVA nominal power and 9.6 KVA in the loop (64% of the nominal power),
I2 = 4 mA + (9.6/15) * 16 mA = 14.24 mA
I.8.9.2 4-20mA loop current (ground insulation):
In the JBUS table, If bit 4 in adress 98 is 1, the first output indicates the ground insulation value (if the “earth
fault detection” option is present). The second output is not used.
•
First output:
If R(
Ω
) earth >= 10M
Ω
, I1 = 4mA
If R(
Ω
) earth <= 1K
Ω
, I1 = 20mA
Between 1K
Ω
and 10M
Ω
, the loop current follows the ground value, according the curve :
Current loop: R(KOhms) = f(I(mA))
1
10
100
1000
10000
20
16
12
8
4
I(mA)
R(
KO
h
m
s)
R (K)
