Mettler Toledo IND780 Guia De Instalacion página 28

IND780 load cell field circuit parameters from control drawing 64069877:
Load cell field circuit parameters from model 745A load cell control drawing:
Default load cell cable values from IND780 terminal control drawing 64069877:
The 2158 junction box PCB was determined not to have significant capacitance or inductance
impact. Values shown below should be used.
Now, compare these values using the formulas provided in the previous section of this chapter and
determine if all three criteria pass or fail. Note that the field circuit parameters for capacitance of the
load cell must be multiplied by the quantity of load cells used. Also note that the field circuit
parameters for the load cell cable must be multiplied by the total load cell cable length.
2-8 METTLER TOLEDO IND780 Division 2 and Zone 2/22 Installation Guide
Terminal model: IND780 terminal (Division 2 approved)
Base model: 2158 VERTEX
Load cell model: METTLER TOLEDO 0745A
Quantity of load cells: 4
Load cell cable length: 50 feet
Junction box PCB p/n: 13640300A
V
V
L
Formula
Vmax or Ui must be ≥ Vsc or Uo
25 VDC ≥ 10.0 VDC
®
(with approved cells)
or U = 10.0 VDC
oc o
I or I = 313 mA
sc o
P = 3.13 W
o
C or C = 100 µF
a o
L or L = 1.2 mH
a o
or U = 25 VDC
max i
I or I = 600 mA
max i
C
= 0 µF
i
L = 29 µH
i
C = 60 pF / foot
cable
= 0.2 µH / foot
cable
C = 0 pF
i
L = 0 µH
i
Pass or Fail
PASS
64063214 | 07 | 02/2018