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23
Intrinsically Safe Wiring
DANGER
: Always lock out and tag electrical circuit breakers while installing or servicing this
equipment and any related equipment. A potentially lethal electrical shock hazard and the
possibility of an explosion or fire from a spark can result if the electrical circuit breakers are
accidentally turned on during installation or servicing.
IMPORTANT
: Intrinsically safe (IS) wiring cannot be run in the same conduit as non-IS wiring.
Conduit knockouts for IS and non-IS module wiring are identified in "Wiring the console and
modules." IS modules can be identified by their blue faceplates and should always be installed to
the right of the moveable isolation barrier. If local codes do not require the use of conduit, cable
glands must be used at all enclosure knock-outs. Gaps larger than 0.06 inches" (1.5 mm) violate
safety approvals. Make sure you provide adequate IS and non-IS wire separation.
The IS modules in the EVO
TM
600 and EVO
TM
6000 consoles were certified as associated
apparatuses using the “Entity Concept.” Under this concept, the IS apparatus (field device) has
assigned parameters which, when properly matched to those of an associated apparatus, will
constitute an intrinsically safe system. If there are none available, values of 60 pF/foot (200 pF/m)
for capacitance per wire pair and 0.2 μH/foot (0.7 μH/m) for inductance may be used. Refer to
the associated apparatus’s control drawing for acceptable cable run length calculations.
The 3WSNS has also been evaluated using the “System Concept” for the specific sensors
indicated on the control drawing 228180035. When these sensors are used, cable must be
limited to 1500" (457 m). Apparatus parameters and IS apparatus parameters are shown below:
Parameter
Associated Apparatus
Comparison
IS Device
Maximum Voltage
Uo
<
Ui
Maximum Current
Io
<
li
Maximum Power
Po
<
Pi
Total unprotected capacitance
Co
>
Ci + Cc
Total unprotected inductance
Lo
>
Li + Lc
Term Definition
Term Definition
Uo
Maximum Output Voltage
Co
Maximum External Capacitance
Ui
Maximum Input Voltage
Ci
Maximum Internal Capacitance
Io
Maximum Output Current
Cc
Cable Capacitance
Ii
Maximum Input Current
Lo
Maximum External Inductance
Po
Maximum Output Power
Li
Maximum Internal Inductance
Pi
Maximum Input Power
Lc
Cable Inductance
Содержание EVO 600
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