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LERBAKKEN 10, 8410 RØNDE DENMARK.
The entity concept
The Transmitter must be installed according to National Electrical Code (ANSI-NFPA 70) and shall be
installed with the enclosure, mounting, and spacing segregation requirement of the ultimate application.
Equipment that is FM-approved for intrinsic safety may be connected to barriers based on the ENTITY
CONCEPT. This concept permits interconnection of approved transmitters, meters and other devices in
combinations which have not been specifically examined by FM, provided that the agency's criteria are
met. The combination is then intrinsically safe, if the entity concept is acceptable to the authority having
jurisdiction over the installation.
The entity concept criteria are as follows:
The intrinsically safe devices, other than barriers, must not be a source of power.
The maximum voltage Ui(V
receive and remain intrinsically safe, must be equal to or greater than the voltage (Uo or V
current (Io or I
or I
) and the power Po which can be delivered by the barrier.
SC
t
The sum of the maximum unprotected capacitance (C
ing wiring must be less than the capacitance (C
The sum of the maximum unprotected inductance (L
wiring must be less than the inductance (L
The entity parameters Uo,V
manufacturer.
For Class II and Class III installations where rigid conduit is not used, seal cable entries against dust and
fibres using a NRTL listed cable gland fitting.
Revision date:
2016-08-03
) and current Ii(I
), and maximum power Pi(Pmax), which the device can
MAX
MAX
) which can be safely connected to the barrier.
a
) which can be safely connected to the barrier.
a
or V
and Io,I
or I
, and C
OC
t
SC
t
Version Revision
V5R0
7501V108-FR
WWW.PRELECTRONICS.COM
) for each intrinsically device and the interconnect-
i
) for each intrinsically device and the interconnecting
i
and L
for barriers are provided by the barrier
a
a
7501QF01
or V
) and
OC
t
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