Honeywell Searchpoint Optima Plus - 4. Electrical Installation; 4.1 Power supply

MAN0905_Issue 7_07/17 Searchpoint Optima Plus with optional HART
®
output
Operating Instructions
2108M0550
25
4. Electrical Installation
4.1 Power supply
TheSearchpointOptimaPlusrequiresavoltagesupplyfromthecontrollerofbetween18Vdcand32Vdc.
The maximum power consumption is 5 W. The maximum loop resistance is 600 Ω. The minimum loop
resistanceforHART
®
operation is 230 Ω.
Note:Incurrentsourcemode,forsupplyvoltagesof18to20Vdcthemaximumloopresistanceis500Ω.
The table below gives the total power consumption for Searchpoint Optima Plus with some common
junction box options.
Termination unit Total power consumption including Searchpoint Optima Plus
HALO** 6 W
XNX 10 W
DVC100 series 6 W
Honeywell Analytics Junction Box 5 W
Ensurethataminimumsupplyvoltageof18VdcismeasuredattheSearchpointOptimaPlus,takinginto
account the voltage drop due to cable resistance.
Themaximumresistanceintheeldcableiscalculatedasfollows:
R loop = (V controller – V detector min) / I detector
Example:
Thecontrollerissupplyinganominal24Vdc(Vcontroller),thedetectorminimumallowablevoltageis18
Vdc (V detector min), therefore the maximum allowable voltage drop between the controller and detector is
6Vdc; this means a voltage drop of 3 V in each core (+ve core and -ve core).
Power consumption of the detector is 5.0 W. The current required to drive the detector at the minimum
voltageis(I=P/V),5.0/18=278mA(Idetector).
So,themaximumeldcableloopresistance(Rloop)=6/0.278=22Ω, or 11 Ω per core, (allowing for
component variations, losses, etc.).
The following tables show the maximum cable distances between the controller and Searchpoint Optima
Plus for a 1.5 mm
2
(16 AWG*) core cable, for different termination unit options, assuming a voltage drop of
3 V in each core. 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.
Termination unit
Total power
consumption
Max Cable Length for 1.5 mm
2
(16 AWG*) core
(Cable resistance 12.7 Ω/km (20.4 Ω/mile))
Metres Feet
HALO** 6 W 709 2326
XNX 10 W 433 1421
DVC100 series 6 W 709 2326
Honeywell Analytics Junction Box 5 W 866 2841
*nearest equivalent
Note:Sufcientoperationalmarginsshouldbeallowed
**ContactHoneywellAnalyticsforavailability