What is an Isolation Transformer?
From voltage spikes and interference to lightning strikes, the electricity coming down the utility pole can be carrying a lot of unwanted noise. The power saw running in your neighbor's garage can create electrical noise for everyone on your block. Sensitive electric and electronic equipment can suffer degraded performance or damage. Isolation transformers are designed to clean up this problem. They remove noise from the electrical system and isolate noisy equipment from the rest of the power grid.
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Identification
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Isolation transformers come in a variety of forms but are usually built into a heavy duty metal box. A power line isolation transformer will have a power cord to plug the unit into a wall outlet and one or more sockets to plug equipment into. They range in size from a box a few inches on each side to industrial transformers weighing more than a ton. Larger units will be permanently wired into the electrical system. Audio isolation transformers are smaller, either built into sound mixers or as a separate box the size of a breath mint can.
Internals
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The transformer itself has a primary and secondary winding like most do, usually with a 1:1 ratio. For most units, the intention is not to change the voltage, it's to protect the equipment from noise on the power line. It generally has a grounded shield between the windings to reduce capacitive coupling between the coils, to block higher-frequency noise. In addition, an electrical surge suppressor and additional radio-frequency noise filtering may be included.
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Benefits
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Equipment connected to an isolation transformer is protected from electrical noise in the power lines. Also, noise produced by motors, switches, and other industrial equipment is prevented from propagating back into the power system. Technicians repairing electronic equipment first connect it to an isolation transformer to prevent shocks caused by faulty grounding. Audio isolation transformers prevent hum from sneaking into sound mixes, and protect people using microphones against shock hazards.
Types
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A general purpose isolation transformer is meant to protect expensive, sensitive electronic equipment such as computers and professional communications gear. Medical-grade isolation transformers are meant to be used in hospitals or in situations more demanding than usual. They're built to higher standards of reliability, noise shielding and safety. Audio isolation transformers are focused on keeping the signal from a microphone or guitar free of electrical noise. Industrial models are generally larger and more robust, meeting larger current and voltage demands. They block noise from high-power equipment like welders and motors.
Warning
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An isolation transformer is not a UPS, or Uninterruptible Power Supply. It will not prevent power from going out completely in case of a brownout or blackout. Depending on the model, it may or may not have surge protection or RF interference filtering. Read the transformer's specifications carefully before using it. Make sure it has the right power and features for your needs.
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