Det-Tronics U7602E Unitized UV Flame Detector/Controller User Manual
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7
Arc Rejection Mode
The arc rejection mode enables the
detector to prevent nuisance fire alarms
caused by UV from shor t-duration
electrical arcs or electrostatic discharge,
while maintaining the ability to reliably
detect the UV given off by a flame. The
arc rejection mode is not recommended
unless these false alarm sources are
present within the application to be
protected. Typical applications that
benefit from arc rejection logic include
electrostatic coating processes and
uncontrolled environments where transient
UV sources can be present, such as
many typical outdoor applications.
The arc rejection algorithm examines the
radiant energy level detected within a
specified unit of time (timed gate). The
output of the detector is determined by
three variables:
— sensitivity level
— gate length
— number of consecutive gates required.
A1508
MOUNTING SCREWS
BULKHEAD
PROGRAMMING
SWITCHES
CLOSED = ON
OPEN = OFF
Figure 9— Electronic Module Mounted Inside Bulkhead
Switch
Function
Closed (On)
Open (Off)
1
OPERATING MODE
Arc Rejection (No High Speed)
Standard (with High Speed)
2
oi
Manual
Automatic
3
FIRE RELAY
Non-latching
Latching
4
FAULT RELAY
Non-latching
Latching
5
NOT USED
6,7
ARC REJECTION LOGIC (SW-1 closed)
Switch No.
6
7
Arc Rejection Level
Consec. Gates
Time
Min. Processing Time
(seconds)
(seconds)
Open
Open
Very High
8
1/16
0.5
Open
Closed
High
4
1/16
0.25
Closed
Open
Medium
4
1/8
0.5
Closed
Closed
Low
4
1/4
1.0
8,9
SENSITIVITY
Switch No.
8
9
Sensitivity Setting
Relative Threshold Equivalent in CPS
Open
Open
Very High
10 cps
Open
Closed
High
25 cps
Closed
Open
Medium
50 cps
Closed
Closed
Low
100 cps
10 to 12
TIME DELAY
Switch
Duration
(seconds)
10
4
Total duration is value of all closed switches added together.
11
2
No high speed output if time duration is used.
12
1
Time delay with all switches open = 0 second
Table 2—Switch Setting Table