Ac Power Wiring; Intrinsic Safety Barriers - Rice Lake IQ plus 810 XPCD Installation Manual

2.5

AC Power Wiring

Electrical connections made in an explosion proof
installation are made through rigid steel conduit
through threaded openings in the back or sides of the
enclosure and must comply with the National
Electrical Code for installation of equipment in
hazardous areas (NEC Article 504, Intrinsically Safe
Systems ).
Connect an electrically separate source of 115 VAC
60HZ to the terminals on the backplate marked
Power In . Observe the polarity of the incoming
wiring and make sure that the terminal marked
is connected to the black wire from the supply.
Hot
Do not apply power at this time.
The drilling and tapping must be to a category IIA/IIB
thread fit. For use;
• Groups C-G applications, five full threads
must engage in the connections.
• Groups A and B, eight full threads must
engage in the connections.
Recheck all connections and make sure there are no
hazards in the surrounding area, and turn on power.
The meter should come on and do a normal lamp test.
Use a DC voltmeter and check the load cell excitation
voltage. The voltage between terminal #1 of the +EX
barrier and terminal #1 of the -EX barrier should be
approximately 10 VDC. Check the field voltage by
measuring the voltage between terminal #1 of the
+SEN barrier and terminal #1 of the -SEN barrier.
This voltage will be lower than the excitation voltage.
With one load cell (350 Ω ), the voltage should be
approximately 8.5 VDC. With four load cells (350 Ω ),
the voltage should be approximately 5.9 VDC. If not,
turn off power and recheck wiring. Make sure the
sense wiring is connected in the field.
10 IQ 810XCPD Installation Manual
2.6

Intrinsic Safety Barriers

The IQ plus 810 XPCD is designed to be used by
personnel already trained and familiar with intrinsic
safety barriers. They are designed to self destruct if a
dangerous condition occurs.
Note:
If you are not trained to work on this equipment,
stop. Call you scale dealer for assistance.
All intrinsic safety barriers have six terminals (shown
below).
AC
AC
#12AWG or larger
conductor to a
designated ground
with resistance < 1 Ω
Figure 2-3. Intrinsic Safety Barrier
Terminals three and four are the intrinsically safe
connections. Devices in the hazardous location are
connected to these terminals. Terminals one and two
are the non-intrinsically safe connections for devices
within the non-hazardous location. The maximum
source voltage applied to these terminals under a fault
condition must not exceed 250 V rms.
Along with the four terminals mentioned above, two
additional screw terminals are provided, one on each
side of the barrier. They are directly attached to the
barrier mounting/grounding system and can be used to
e s t a b l i s h a r e d u n d a n t g r o u n d s y s t e m o r f o r
terminating shields. On single channel barriers they
are also internally connected to terminals two and
four.
Since a common housing is shared between single,
dual, and application dedicated barriers, refer to the
schematic printed on the side of each barrier to
determine the designation of the floating and
grounded terminals.
INDICATOR SIDE
PIN #1 ON ALL BARRIERS
1 2 1 2 1 2 1 2 1 2 1 2
160 mA 160 mA 160 mA 160 mA 160 mA 160 mA
160 mA 160 mA 160 mA 160 mA 160 mA 160 mA
Intrinsic Intrinsic Intrinsic Intrinsic Intrinsic Intrinsic
Safety Safety Safety Safety Safety Safety
Barrier Barrier Barrier Barrier Barrier Barrier
3 4 3 4 3 4 3 4 3 4 3 4
PA/
PA/
LOAD CELL SIDE
PIN #3 ON ALL BARRIERS