Digital linear heat detection 

by Protectowire


Standard Digital (PHSC)

The Standard Digital Protectowire Heat Sensitive Cable (PHSC) Linear Heat Detector can best be described as a continuous run of spot heat detectors. It is capable of sensing heat anywhere along its length and initiates an alarm once its fixed activation temperature is reached.

The Standard Digital (PHSC) Linear Heat Detector works in the following manner. Once the ambient temperature meets or exceeds its fixed temperature, the heat sensitive polymer weakens, which in turn allows the twisted spring steel conductors to make contact, which results in an electrical short that triggers an alarm signal.

The Standard Digital (PHSC) Linear Heat Detector is designed to be used on a compatible fire alarm control module or panel.

All Protectowire Linear Heat Detectors must be installed in accordance with applicable sections of NFPA 72 or as required by the local AHJ.

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Unique advantages of Protectowire Linear Heat Detectors include:

  • Detects heat at any point along its length

  • Low maintenance

  • Outer jackets resist corrosion, chemicals, moisture, and extreme temperatures

  • Can be installed close to hazards to provide rapid response

  • Long service life

What is the primary difference between Protectowire PHSC and PLR Digital Linear Heat Detectors?

Protectowire PHSC series is manufactured using spring steel conductors, while the PLR series is manufactured with low resistance tri-metallic conductors that are engineered to enable longer detector zone lengths on other manufacturers' control equipment. The amount of Protectowire (PHSC or PLR series) that can be installed on another manufacturers' control equipment is directly determined by the maximum loop resistance of the equipment’s initiating device circuit. Protectowire’s PHSC digital linear heat detectors have an approximate resistance of 0.185 Ohms per foot (0.607 Ohm per Meter). Protectowire’s PLR digital linear heat detectors have an approximate resistance of 0.058 Ohms per foot (0.191 Ohm per Meter). The PLR series detectors allow for approximately 3x longer lengths on the same initiating device circuit.

Can Protectowire Linear Heat Detectors with different alarm temperature ratings be installed in the same zone?

Yes. Protectowire offers two series of detectors capable of supporting different activation temperatures on the same series initiating device circuit. This allows a single Protectowire Linear Heat Detector zone to protect multiple areas with different ambient temperatures. The PHSC Series can support 135°F, 155°F, 190°F, 220°F, 280°F and 356°F being spliced into the same initiating device circuit. The PLR Series can support 155°F and 190°F being spliced into the same initiating device circuit.

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