Det-Tronics TXL Series Gas Transmitter - Manual (Page 11)

If battery back-up power is required, use a float type
battery charging system. If using a battery back-up
power system, calculate “normal, alarm, and recharge”
battery operation duration requirements if applicable,
then select a charger and batteries that will meet these
requirements.
If an existing source of 24 VDC power is being utilized,
verify that no high levels of noise, ripple, or electromag-
netic interference are present on the power conductors
or the system earth ground. Marginal input power
sources can result in nuisance faults and insufficient
detector sensitivity.
Always use proper cable type and diameter for input
power as well as for output signal wiring. Determine if
voltage drops will occur within the installation. The TXL
detector should receive 24 VDC at the detector.
Consider the use of field-installed power supplies or
power distribution cabinets if long power cable runs
result in unacceptable voltage drops. A properly sized
master power fuse or breaker on the system power cir-
cuit is highly recommended.
CALCULATING MAXIMUM CABLE LENGTH
The maximum cable length is determined by the capac-
itance and inductance of the cable, and must be equal
to, or less than, the capacitance (Ca) and inductance
(La) values indicated on the barrier being used.
Maximum Distance = Ca on barrier
Cable capacitance / ft.
Maximum Distance = La on barrier
Cable inductance / ft.
NOTE
Because Ci = 0 and Li = 0, they are not part of this
formula.
The shortest of these two distances is the maximum
wiring distance.
NOTE
If cable parameters are unknown, 60 pf / ft. and
0.2 µh / ft. must be used to calculate maximum dis-
tance.
Do not exceed 4000 feet total field cabling length using
20 AWG conductor size.
WIRING TERMINATION
Ensure that all cables are terminated properly. The
required screw terminal torque range is 0.4-0.5 Nm.
Connect the white wire to pin 2 (+) and the black wire to
pin 1 (–) inside the TXL enclosure. See Figure 2.
For toxic sensors, remove the jumper wire from the sen-
sor plug, then plug the sensor into the 6-pin connector
on the inside of the enclosure cover. See Figure 3.
Connect the white wire from pin 1 of the TXL and the
black wire from pin 2 of the TXL to the barrier as shown
in Control Drawing No. P-1115. Connect the shield to
the barrier case.
Connect a length of two-conductor shielded cable from
the barrier to the controller as shown in Control Drawing
No. P-1115. Connect the shield to the barrier case at
the barrier end and to the controller case at the con-
troller end. Connect the barrier and controller cases to
earth ground at the controller.
Refer to the controller manual for instructions on wiring
the controller.
9 95-8541 1.1
BLACK WIRE TO PIN 1 (–)
WHITE WIRE TO PIN 2 (+)
CONNECT SENSOR
PLUG HERE
A2128
Figure 2—Inside View of the TXL Detector
REMOVE JUMPER WIRE
FOR TOXIC SENSORS A2129
Figure 3—Sensor Plug