Power - Honeywell Sensepoint XCD Technical Manual

Sensepoint XCD Technical Manual

6.3 Power

The Sensepoint XCD transmitter requires a power supply from the controller of between
16Vdc and 32Vdc. Ensure that a minimum supply of 16Vdc 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 16Vdc (V
controller and detector is 8Vdc; this means a voltage drop of 4V in each core (+ve core
and -ve core).
+20V
(wrt Controller 0V)
4-20mA
16V
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 / 16 = 312.5mA (I detector).
So, the maximum field cable loop resistance (R loop) = 8 / 0.31 = 26 Ohms, or 13 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
+4V
Diagram 8: 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)
Table 2: Maximum cable distances
), the detector minimum allowable
controller
Field Cable (L)
Maximum Cable length (L)
Meters
353
666
1023
1287
1621
17
SPXCDHMANEN Issue 2
+24V
Signal
Controller
0V
Feet
1158
2185
3356
4222
5318