Det-Tronics UD10 DCU Emulator FlexVu Universal Display Unit - Manual (Page 9)

7 95-8656 4.2
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POwER SUPPLY REQUIREmENTS
Calculate the total gas detection system power
consumption rate in watts from cold start-up. Select a
power supply with adequate capability for the calculated
load. Ensure that the selected power supply provides
regulated and filtered 24 Vdc output power for the entire
system. If a back-up power system is required, a float-type
battery charging system is recommended. If an existing
source of 24 Vdc power is being utilized, verify that system
requirements are met. The acceptable voltage range is
18-30 Vdc measured at the input to the UD10-DCU.
wIRINg CabLE REQUIREmENTS
Always use proper cabling type and diameter for input
power as well as output signal wiring. 14 to 18 AWG
shielded stranded copper wire is recommended. Correct
wire size depends on the device and wire length. Refer to
the appropriate Appendix for additional information. The
maximum cable length from power source to UD10-DCU
is 2000 feet. Maximum cable length from UD10-DCU to
sensor is 2000 feet.
noTe
The use of shielded cable in conduit or shielded
armored cable is highly recommended. In
applications where the wiring is installed in
conduit, dedicated conduit is recommended.
Avoid low frequency, high voltage, and
non-signaling conductors to prevent nuisance
eMI problems.
CautIon
The use of proper conduit installation techniques,
breathers, glands, and seals is required to prevent
water ingress and/or maintain the explosion-proof
rating.
wIRINg PROCEDURE
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Since the UD10-DCU can be used with a variety
of different detection devices, information that
is specific to each detector model (wiring,
calibration, HART menus, etc.) is covered in an
Appendix that is dedicated to that device. Refer
to the appropriate Appendix at the back of this
manual for specific information when wiring the
detection system. For information on devices
not covered in an Appendix, refer to the manual
provided by the device’s manufacturer.
Connect 24 vdc power lead wires and communication
network cable to the appropriate terminal block. Refer
to Figure 2 for an illustration of the UD10-DCU wiring
terminal board.
COM 1 - Communication network connections:
Connect to COM 2 terminals of the next
device on the loop, A to A and B to B.
COM 2 - Communication network connections:
Connect to COM 1 terminals of the previous
device on the loop, A to A and B to B.
24 VDC - Connect the “+” terminal to the positive
side of the 24 vdc power source. (Both “+”
terminals are connected internally.)
Connect the “–” terminal to the negative
side of the 24 vdc power source. (Both “–”
terminals are connected internally.)
Figure 3 shows a UD10-DCU Wired to a generic
sensing device. Refer to the appropriate Appendix for
information regarding a specific detector.
grease/Lubrication
To ease installation and future removal, ensure that all
junction box covers and sensor threads are properly
lubricated. If the need arises for additional lubrication,
use either Lubriplate grease (see Ordering Information
for part number) or Teflon tape. Avoid the use of silicone
grease.
ShIELD CONNECTIONS
The UD10 provides terminals for proper grounding of
wiring cable shields (located on the sensor, 4-20 mA,
and operating power terminal blocks). These shield
terminals are not connected internally, but are connected
to ground through capacitors. The capacitors ensure an
RF ground, while preventing 50/60 Hz ground loops.
Ground all shields as shown in the wiring examples
throughout this manual.
Important
For proper grounding, all junction boxes / metal
enclosures must be connected to earth ground.
The following are required for installations requiring CE
Mark compliance:
• For shielded cable installed in conduit, attach the wire
shields to the “shield” connections on the terminal
blocks, or to earth ground on the case.
• For installations without conduit, use double shielded
cable. Terminate the outer shield to earth ground on
the case. Terminate the inner shield to the “shield”
connection on the terminal blocks.