Det-Tronics LS2000 - Optional Relays

19 95-87142.2
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
Refer to “Alarm Relays” in the
Specications 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 0.7 inch (18 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 10 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 11 shows the wiring terminal configuration
for the LS2000 transmitter.
Figure 12 shows the wiring terminal
configuration for the LS2000 receiver without
relays.
Figure 13 shows the wiring terminal
configuration for the LS2000 receiver with relays.
Figures 14 through 17 show the 4-20 mA
output of the LS2000 receiver in various wiring
schemes.
See Figure 18 for benchtop test wiring.
NOTE
For proper HART communication, it
is required that an analog signal loop
resistance of 250 to 500 ohms be
present at the receiver analog output
terminals. For LS2000 systems using
HART communication, the maximum
wiring distance is 2,000 feet. No external
resistance needs to be added to the
transmitter wiring for proper HART
operation.
A pair of HART connector pins is provided for
ease in connecting a HART handheld device.
See Figure 19 for location.