Shielded VS Non-Shielded Master Alarm Cable

Customers have asked why Tri-Tech Medical master alarm signal wire cable specifications call for non-shielded wire cables when our competitors require shielded wire cables. Tri- Tech Medical master alarm signal wire cables do NOT need to be shielded. The reason is, our master circuit boards incorporate opto-isolators at each master signal wire connection point which our competitors do not have on their boards. Yes, they add cost to our circuit boards, but they also provide additional benefits in the form of protection from outside voltage spikes which could damage the circuit board and filtering out false or nuisance alarms which may be created by induced voltage from outside sources. The opto-isolators transfer electrical signals between the circuits by using light and they prevent high voltages and electronic noise from affecting the system receiving the signal.


Master Alarm

What is an opto-isolator? An opto-isolator is an electronic device that prevents high voltages from components in one side of a circuit from damaging or interfering with components on the other side of the same circuit. Opto-isolators regulate voltage levels by converting electricity into a beam of light. This prevents voltage spikes from impacting more than a single circuit and decreases the overall interference and noise that occurs with traditional communications connections.

One of the drawbacks of using shielded cable is the shielding actually acts as an antenna gathering unwanted electronic noise to the grounded end of the shielding. Shielded cable is also more expensive and stiffer (making it more difficult to install), and has a larger diameter (taking up more space in conduit and cable trays).

This is why Tri-Tech Medical master alarm systems do not require shielded wire cables.

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