Isolation Transformer Explained

By R. W. Hurst, President, The Electricity Forum

Isolation Transformer
Isolation Transformer

An isolation transformer is comprised two copper coils which are wound about each other and are independently supplied each by their own electrical power source. Why is it called an "isolation transformer”?  This is because an "isolation transformer" is a transformer that isolates a circuit from an alternating current. How is this accomplished? This is accomplished by the separation two different circuits with an induction loop, thereby decreasing the AC's voltage prior to it reaching the circuit.

How An Isolation Transformer Operates
An isolation transformer works in a similar way to other kinds of transformers. An isolation transformer is manufactured with 2 electromagnets which are wound about each other so that the primary coil induces a current in the secondary coil. It just so happens that if the primary transformer coil is wound more times than the secondary transformer coil, the voltage would be decreased. Alternately, if the secondary transformer coil is wound more than the primary transformer coil, then the voltage would be increased. That is why primary and secondary windings must be wound equally. According to the US Department of Energy, these electrical isolation distribution transformers provide an electrostatic shield or grounded shield for ac power supplies because they eliminate interference caused by ground loops.

Internal low-impedance isolation transformer component offers 100% isolation from the input AC line. Full UL2601-1 medical grade listing with hospital-grade plug and outlet receptacles makes Isolator Hospital Grade transformers ideal for the protection of sensitive electronic equipment in patient-care areas. Isolation transformer with Faraday shield reduces the cumulative leakage current of the Isolator and connected equipment to levels below 300 microamps. Secondary neutral to ground bonding virtually eliminates common mode noise, providing an isolated neutral-ground reference for sensitive equipment and an inexpensive alternative to the installation of dedicated circuits and site electrical upgrades. Some isolation transformers remove EMI/RFI noise, utility switching transients, and harmonics generated by other onsite loads and utility or lightning related surge conditions. Additional surge suppression components placed at the line input and output combined with full line isolation offers continuous filtering of a full range of power line noise in all modes. Active transformer filtering offers continuous common-mode noise rejection with no wearable parts, uniquely able to reduce surges in the worst of power environments to harmless levels.

Ideal Applications:

  • Computers and peripherals
  • Telecommunications
  • Medical
  • Laboratory instrumentation
  • Process control
  • Office automation
  • Building Security and as a bypass transformer for UPS systems

Read Our Other Transformer Pages: Potential Transformer Explained, Control Transformer Explained, Current Transformer Basics, Dry Type Transformers Explained, Current Transformer Explained, When To Use a Step Down Transformer