Power - Honeywell Sensepoint XCD RFD Technical Handbook

Sensepoint XCD RFD Technical Manual
6.3 Power for UL/CSA Version
The Sensepoint XCD transmitter(U L /CSA versions)requires a power supply from the controller
of between 12Vdc and 32Vdc. Ensure that a minimum supply of 12Vdc is measured at the
sensor,
taking into account the voltage drop due to cable resistance.
The maximum loop resistance in the field cable is calculated as follows
R = (V – V
loop controller
Example;
The controller is supplying a nominal 24Vdc
(V
voltage is 12Vdc
controller and detector is 12Vdc; this means a voltage drop of 6V in each core (+ve core
and -ve core).
+1 8 V
(wrt Controller 0V)
4-20mA
12V
XCD
(min)
(wrt Controller 0V)
Power consumption of the detector is 5.0W. The current required to drive the detector at
the minimum voltage is (I = P / V), 5.0 / 12 = 416.7 mA (I detector).
So, the maximum ieldcable loop resistance (R loop) = 12 / 0.42 = 28.8 Ohms, or 14.4 Ohms
per core, (allowing for component variations, losses, etc.).
The following tables show the maximum cable distances between the controller and
transmitter assuming a voltage drop of 4V in each core and for different cable parameters.
The tables are examples only and actual cable parameters and source power supply
voltage for the application should be used to calculate the maximum cable distance
allowed at the installation site.
Typical cable data
Cable size
(cross sectional area)
0.5mm2 (20AWG*)
1.0mm2 (17AWG*)
1.5mm2 (16AWG*)
2.0mm2 (14AWG*)
2.5mm2 (13AWG*)
*nearest equivalent
) / I
detector min detector
)
, therefore the maximum allowable voltage drop between the
detector min
+6V
Diagram 7: Power Connection
Cable resistance
Ω/km (Ω/mi)
36.8 (59.2)
19.5 (31.4)
12.7 (20.4)
10.1 (16.3)
8.0 (12.9)
**example for 24Vdc supply voltage
Table 2: Maximum cable distances
(V )
, the detector minimum allowable
controller
Field Cable (L)
Maximum Cable length (L)
Meters
353
666
1023
1287
1621
20
SPXCDHMRFEN Issue 4_08-2016
+24V
Signal
Controller
0V
Feet
1158
2185
3356
4222
5318