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To understand how Protectowire
Linear Heat Detector works, it is important to
understand the basic construction of the detector. |
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1. Outer Jacket
Protectowire Linear Heat Detector is available with
various outer jackets suitable for different
environmental conditions. The outer jacket
determines the detectors environmental
characteristics. It is important that a suitable
jacket type be selected for the environment which
the detector will be subjected to. |
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2. Mylar Wrap
Beneath the outer jacket is a Mylar™ wrap which
provides additional protection for the inner
conductors of the detector. |
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3.
Heat Sensitive Polymer
A Heat sensitive polymer coats
the inner conductors of the Protectowire Linear Heat
Detector insulating them from each other. The
polymer is designed to be physically stable up to
the rated alarm set point temperature of the
detector. If the rated alarm temperature is reached
or exceeded at any point along the detector, the
polymer at that point becomes soft. This softening
allows the inner conductors to contact each other
producing an alarm condition (short) on the
initiating circuit. |
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4. Steel Twisted Pair
A twisted pair of steel conductors comprises the
core of Protectowire Linear Heat Detector. The twist
provides evenly distributed tension between the
conductors which assures the detector actuates once
it's alarm temperature is reached. The nature of a
twisted pair also adds a measure of protection from
induced electrical interference such as EMI and RFI
which could effect monitoring circuitry. Steel
conductors are used not only to make a durable
detector, but for their unique electrical
characteristics, which allow for Alarm Point
Location. |
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Monitoring
of Protectowire Linear Heat Detector
utilizes conventional initiating device circuits. |
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1. Supervision
The entire length of Protectowire Linear Heat
Detector is supervised by a conventional initiating
device circuit. A small current is continuously
passed through the detector and end of line resistor
(ELR). The end line resistor limits the amount of
current to a preset level which the monitoring
circuit is configured to treat as a normal
condition. |
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2. Fault conditions
If an open circuit condition occurs anywhere in the
loop, current is no longer allowed to flow through
the Protectowire Linear Heat Detector. The
monitoring circuit is configured to treat this as a
fault or trouble condition. |
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3.
Alarm Conditions
If a portion of the Protectowire Linear Heat
Detector is exposed to heat above it's rated alarm
temperature the heat sensitive polymer breaks down
and a short occurs at that point. This bypasses the
end line resistor greatly increasing the current
flow through the loop. The monitoring circuit is
configured to treat this as an alarm condition. |
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3.
Alarm Point Location - Protectowire FireSystems
Control Panel Exclusive Feature
If the Protectowire FireSystem control equipment is
configured with the Alarm Point Location Option, a
linear distance representing the length of
Protectowire Linear Heat Detector from the start of
the Protectowire portion of the circuit to the
actuated point can be displayed at the control
panel. |
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| For More on how
Alarm Point Location Works
Click Here |
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