6.3
95-8714
20
POWER WIRING SIZE AND MAXIMUM
LENGTH
1. To ensure proper operation, LS2000 power
terminals and 4-20 mA terminals must receive
18 Vdc minimum. 24 Vdc is recommended.
2. Always determine voltage drops that will
occur to ensure that 24 Vdc is delivered to the
LS2000.
3. Normally, nothing smaller than 18 AWG, 1.0
mm
2
is recommended by Det-Tronics for
LS2000 power cabling.
Wire size requirements are dependent upon
power supply voltage and wire length.
The maximum distance between the LS2000
detector and its power supply is determined
by the maximum allowable voltage drop
for the power wiring loop. If the voltage drop
is exceeded, the device will not operate. To
determine the maximum power loop voltage
drop, subtract the minimum operating voltage
for the device (18 Vdc) from the minimum output
voltage of the power supply.
To determine the actual maximum wire length:
1. Divide the maximum allowable voltage drop
by the maximum current draw of the LS2000
(0.771 A),
2. Divide by the resistance of the wire (ohms/
foot value available in wire manufacturer’s
specification data sheet),
3. Divide by 2.
For example: Consider an installation using 18
AWG wiring with a power supply providing 24
Vdc.
Power supply voltage = 24 Vdc,
LS2000 minimum operating voltage = 18 Vdc
24 – 18 = 6 Vdc
Maximum Voltage Drop = 6
Maximum Current = 0.771 A
Wire Resistance in Ohms/Foot = 0.006523
6 ÷ 0.771 ÷ 0.006523 ÷ 2 = 596 feet
OPTIONAL RELAYS
Optional relay contacts are “dry,” meaning that
the installer must provide the voltage to the
common terminal of the relay output.
AC voltage should not be switched directly
using the LS2000 relays. The use of an external
relay is required if AC voltage must be switched
by the LS2000 relays. Note: External relay is not
covered by any Certifications.
In order to change alarm relay settings from the
factory default settings, it is recommended to
use a HART Field Communicator. Contact the
factory for further assistance.
NOTE
Re fe r to “A l a rm Re l ays ” i n t h e
“Specifications” section of this manual
for important information regarding alarm
relays.
WIRING PROCEDURE
For systems using conduit, modules must be wired
using a short piece of suitable flexible conduit to
allow optical alignment of the modules. Conductor
insulation should be stripped off with a bare
conductor length of 0.2 inch (5 mm) minimum and
0.35 inch (9 mm) maximum. Screw terminal torque
range is 3.5–4.4 lb.-in. (0.4–0.5 N•m).
Cable shield, if used, should be properly
terminated. If not terminated, clip the shield wire
off short and insulate it within the detector housing
to prevent the shield wire from accidentally
contacting the detector housing or any other wire.
Figure 12 shows the wiring terminal strip located
inside the detector’s integral junction box.
NOTE
The LS2000 housing must be electrically
connected to earth ground. A dedicated
earth ground lug is provided for this
purpose.
Figure 13 shows the wiring terminal configuration
for the LS2000 transmitter.
Figure 14 shows the wiring terminal configuration
for the LS2000 receiver without relays.
Figure 15 shows the wiring terminal configuration
for the LS2000 receiver with relays.
Figures 16 through 19 show the 4-20 mA output
of the LS2000 receiver in various wiring schemes.
See Figure 20 for benchtop test wiring.
