Intrinsically Safe Equipment And Safety Barrier; Wiring Of Intrinsically Safe Equipment And Safety Barrier - Nagano Keiki EJ15 User Manual

*1 Install the EJ15 during piping so that the main body (fitting) is grounded as it is required to do so (For
the terminal box type, the EJ15 main body can also be grounded from the M4 screw portion provided on
the outer surface). If the piping (EJ15 unit) cannot be grounded, use the ground terminal of this product
(M12 connector type: cable shielded wire/terminal box type: terminal block ground terminal) to ground
the product. However, when both the EJ15 body and earth terminal are grounded, provide single point
grounding so that there is no potential difference.
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■ 7.5 Intrinsically Safe Device and Safety Barrier
Intrinsically safe performance can be assured only when intrinsically safe device (EJ15)
is paired with the safety barrier in a manner so that the conditions in the following two
tables below are met. Therefore, be sure to comply with the combination conditions in
"3.2 Intrinsically safe specifications".
Combination Conditions for Safety Holding Rating
EJ15
safety holding rating
Maximum input voltage (Ui)
Maximum input current (li)
Maximum input power (Pi)
Parameters for EJ15 and wiring
Maximum internal inductance (Li)
+ Wiring inductance (Lc)
Maximum internal capacitance (Ci)
+ Wiring capacitance (Cc)
■ 7.6 Wiring for Intrinsically Safe Device and Safety Barrier
Intrinsically safe device (EJ15) and the safety barrier must be wired so that voltages and
currents are not induced that could impair the intrinsically safe construction of
Intrinsically Safe Circuit due to electromagnetic or electrostatic induction.
If you use a zener barrier, a single Class A grounding work is
required under the intrinsically safe regulations.
Please note when you use a recommended Zener barrier
(MTL7787+) that the load resistance of such barrier will be
added to the load resistance that the user can connect as
shown in the following formula: [R
cable line resistance) (E: power supply voltage).
< Table 7-4 >
Parameter Combination Conditions
< Table 7-5 >
CAUTION
= 50E-900] Ω (including
L
Combination
condition
safety holding rating
≥
Maximum output voltage (Uo)
≥
Maximum output current (lo)
≥
Maximum output power (Po)
Combination Safety barrier parameter
condition
≤
≤
29
Safety barrier
Maximum external
inductance (Lo)
Maximum external
capacitance (Co)
TY-EJ15-003A Rev.2