Yokogawa EJA118 - Manual (Page 25)

IM 1C22H1-01E 5-4
5. WIRING
᭿ Flameproof metal conduit wiring
• A seal fitting must be installed near the terminal box
connection port for a sealed construction.
• Apply a non-hardening sealant to the threads of the
terminal box connection port, flexible metal conduit
and seal fitting for waterproofing.
F0510.EPS
Non-hazardous area
Hazardous area
Flameproof
heavy-gauge
steel conduit
Tee
Drain plug
Seal fitting
Gas sealing device
Flameproof flexible
metal conduit
Apply a non-hardening
sealant to the threads of
these fittings for
waterproofing
After wiring, impregnate the fitting
with a compound to seal tubing.
Figure 5.4.2d Typical Wiring Using Flameproof Metal
Conduit
5.5 Grounding
(a) Grounding should satisfy JIS Class 3 requirements
(grounding resistance, 100
Ω
or less). Grounding is
required for JIS flameproof type and intrinsically
safe type.
(Note) If equipped with built-in Lightning Protector, grounding
should satisfy Special JIS class 3 requirements (grounding
resistance, 10
Ω
or less).
(b) There are ground terminals on the inside and
outside of the terminal box. Either of these termi-
nals may be used.
(c) Use 600 V grade PVC insulated wires for ground-
ing.
Ground terminal
Ground terminal
Transmitter terminal box
F0511.EPS
Figure 5.5 Ground Terminals
5.6 Power Supply Voltage and
Load Resistance
When configuring the loop, make sure that the external
load resistance is within the range in the figure below.
(Note) In case of an intrinsically safe transmitter, external load
resistance includes safety barrier resistance.
,
600
250
0 10.5 16.4 24.7 42
External
load
resistance
R (
Ω
)
Power supply voltage E (V DC)
F0512.EPS
Communication
applicable range
BRAIN and HART
R=
E–10.5
0.0236
Figure 5.6 Relationship between Power Supply Voltage
and External Load Resistance