Grounding And Bonding - Mettler Toledo IND560 Serie Guia De Instalacion

IND560xx Terminal Division 2 and Zone 2/22 Installation Manual
load cells used. The inductance value is the same for 1 through 12 load cells. Also
note that the field circuit parameters for the load cell cable must be multiplied by
the total load cell cable length.
U / V
i
12 VDC ≥ 10.0 VDC
I / I
i max
600 mA ≥ 313 mA
C + C
i
C
C
C
(0 µF + 0 µF + 0.003 µF) ≤ 1 µF
L + L
i
L
L
L
(0.029 mH + 0 mH + 0.01 mH) ≤ 0.6 mH
In addition to the formulas above, the temperature rating of the IND560xx terminal
must be checked against the AIT (Auto Ignition Temperature) of the hazardous
product. For this example, the hazardous product has an AIT of 200°C (393°F),
which is higher than the rating of the IND560xx terminal approval value of 135°C
(211°F). This indicates the temperature comparison test passes.
Since all four field circuit parameters compare favorably and pass the formula
evaluation and the temperature comparison test passes, the products listed in this
example may be safely installed into a Division 2 area. They must be installed
according to the IND560xx control drawing 72186884CR using all pertinent local
and national standards.

Grounding and Bonding

All grounding (earthing) and equal potential bonding connections must be made
according to local regulations based upon the country of installation. Refer to local
codes and the control drawing or installation drawing in the Appendix section of
this manual for more specific information regarding grounding. It is typical that
regional regulations require that all connected pieces of equipment in the system
be bonded together and grounded to a single point. Wire loops, external screws
and star washers have been provided in the installation accessory kits of each
terminal to assist in field installation. Figure 2-4 indicates the locations for
grounding and bonding connections on the panel mount and harsh enclosure
terminals.
2-8
Formula
must be ≥ V / U
max oc o
must be ≥ I / I
o sc
≤ C
cable a
= 0 µF * 4 cells = 0 µF (load cells)
i
= 0 µF (junction box)
i
= 60 pF / foot * 50 feet = 3000pF = 0.003 µF
cable
≤ L
/ L
cable a o
= 29 µH (load cells) = 0.029 mH
i
= 0 µH (junction box)
i
= 0.2 µH / foot * 50 feet = 10 µH = 0.01mH
cable
Pass or Fail
PASS
PASS
PASS
PASS