DW1500110 Rev.K1
Sep 18 2015
2
1.3
EVCA-P features
* Low profile, stylish appearance
* Low monitoring current
* Supplied with protective dust cover
* OMNIVIEW
TM
360
o
LED Indicator for fire alarm indicators
* Photoelectric detector, detecting visible particles of combustion
Section 2
–
GENERAL OPERATION
The
EVCA-P
chamber consists of a light emitting diode (LED) and photodiode arrangement. The chamber contains a
unique design which allows smoke to enter the chamber while preventing external light from affecting the photodiode.
The
EVCA-P
has chemically etched, stainless steel insect screen therefore reducing the ingress of insects and
airborne contaminants. The chamber is designed so that the light emitted by the LED is not directed to the photodiode.
The LED pulses every 8 seconds to maintain a low monitoring current. A quick charging time (20 seconds) is also
achieved. The detector incorporates an alarm verification function which requires two successive pulses before an
alarm is given. The interval between the first and second pulse is automatically reduced to four seconds after the first
alarm level is monitored.
In the event of fire, particles of smoke enter the chamber and scatter the light in the active area of the chamber. The
scattering effect increases the light in the chamber, causing more light to be detected by the photodiode.
