h. Detector tuning shall be automatic, with temperature compensation.
i. Detector shall have user selectable sensitivity settings.
j. Detector response time shall be 15 milliseconds or less.
k. Detector output shall be a dry form C contact set, rated a minimum of
0.25 A at 24 Volts dc.
l. Detector enclosure rating shall be NEMA 4X or better.
m. Detector shall be capable of operating in a humidity range of 0 to 95
percent and a temperature range of
-40 to +77 degrees C
-40 to +170
degrees F
.
n. Detector shall be capable of operating from 120V/60Hz power, or be
provided with appropriate power module/assembly and appurtenance, which
are suitable for operation with 120V/60Hz.
2.11.2 Induction Loops
Induction loops may be used for vehicle presence detection, wrong-way
detection, and point over-speed detection. Induction loops shall be
capable of detecting passenger vehicles, motorcycles, and high bed trucks.
Tests for all three types of vehicles shall be conducted on each installed
loop during the Performance Verification Test.
a. Tuning: automatic, with temperature compensation.
b. Loop input: to withstand minimum 2000V, both normal and common modes.
c. Loop Sensing frequency: minimum four user selectable frequencies to
minimize cross talk with adjacent loops.
d. Sensitivity: user selectable, minimum 12 ranges, 20 to 2500 micro
henries with a Q factor of minimum 5.
e. Diagnostic: provide diagnostics and related indication for short and
open loop circuit.
f. Detector output: dry form C contact set, rated a minimum of 0.25 A at
24 Volts dc.
g. Operating humidity: 0 to 95 percent.
h. Operating temperature:
-40 to 77 degrees C
-40 to 170 degrees F
.
i. Vibration:
NEMA TS-2
-2.1.9 or better.
j. Shock:
NEMA TS-2
-2.1.10 or better.
k. User selectable operation modes: presence, pulse on entrance, pulse on
exit - factory set on presence mode.
l. User selectable operation: Fail Safe or Fail Secure - factory set at
Fail Safe.
m. User selectable sensitivity boost feature, which boosts sensitivity
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