Det-Tronics PIRECL Infrared Hydrocarbon Gas Detector PointWatch Eclipse User Manual

Page 9

95-8526

14.2

Calibration gas port Cover
A protective cover for the calibration gas injection port is

provided to ensure that contaminants are not accidently

introduced into the Eclipse optics. Ensure that this cover

is properly installed over the port when calibration is not

being performed.

NOTE

Failure to install the calibration gas port cover or
the use of a damaged cover may result in nuisance
faults and require cleaning the detector optics.

24 VDC power SUpply reQUireMentS
Calculate the total gas detection system power

consumption rate in watts from cold start-up. Select a

power supply with adequate capability for the calculated

load. Ensure that the selected power supply provides

regulated and filtered 24 Vdc output power for the entire

system. If a back-up power system is required, a float-

type battery charging system is recommended. If an

existing source of 24 Vdc power is being utilized, verify

that system requirements are met.

wiring Cable reQUireMentS
Always use proper cabling type and diameter for input

power as well as output signal wiring. 14 to 18 AWG

shielded stranded copper wire is recommended.

Always install a properly sized, master power fuse or

breaker on the system power circuit.

NOTE

The use of shielded cable in conduit or shielded
armored cable is required. In applications where
the wiring is installed in conduit, dedicated conduit
is recommended. Avoid low frequency, high
voltage, and non-signaling conductors to prevent
nuisance EMI problems.

CaUtIon

The use of proper conduit installation techniques,
breathers, glands, and seals is required to prevent
water ingress and/or maintain the explosion-proof
rating.

power wiring Size anD MaxiMUM length
1. The Eclipse detector must receive 18 Vdc

minimum to operate properly. 24 Vdc minimum is

recommended.

2. Always determine voltage drops that will occur to

ensure that 24 Vdc is delivered to the Eclipse.

3. Normally, nothing smaller than 18 AWG (0.75 mm

)

is recommended by Det-Tronics for Eclipse power

cabling.

Wire size requirements are dependent upon power

supply voltage and wire length.

The maximum distance between the Eclipse 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 Eclipse (0.31 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,

Eclipse minimum operating voltage = 18 Vdc

24 – 18 = 6 Vdc

Maximum Voltage Drop = 6

Maximum Current = 0.31 A

Wire Resistance in Ohms/Foot = 0.006523

6 ч 0.31 ч 0.006523 ч 2 = 1484 feet

NOTE

For FM/CSA/ATEX Certified systems using HART
communication, the maximum wiring distance is
2000 feet.

Maximum Voltage Drop

Maximum Current

Wire Resistance in Ohms/

Foot

Maximum Wire Length =

Maximum Power Loop

Voltage Drop =

Power Supply Voltage

Minus

Minimum Operating Voltage