Isolation Transformer

• An isolation transformer detaches the equipment ground and the respective AC power ground. It consists of two coils which are not in contact, but the electro-magnetic field induces a voltage from one coil to the other. As a result, power is transmitted from one coil to another without touching the ground. The drawback of this method is that it solves power-related problems only but is useless to solve RGB or video signal problems.
  
  So, if the potential different two grounds affect the RGB or video signal, this method cannot rectify the hum. Consequently, in modern video equipment, even though they are provided with isolation transformers at the power input location and the ground loop, hum is unavoidable.
  
  

Optical Isolator

• Here, LED is used as a transmitter of video signals; the LED blink in a pattern and the light wave stimulates certain electrical response from the optically coupled transistor base, i.e., the photo detector. Due to lack of physical connection between LED transmitter and photo detector, no ground is required to receive the signal. So, the question of hum does not arise. However, if the bandwidth of the optical ground loop isolator is poor, it results in fuzzy images and poor linearity.
  
  

Operational Amplifier

• Operational amplifiers amplify the difference between two input lines, eliminating common mode noise between incoming signals. It is the only method to maintain a wide bandwidth of signals in the system along with removing ground loop problems related to power and the video. Bandwidth of up to 350 MHz can be reached using this technology and system linearity is better than or equal to one percent.
  
  

Plastic Isolation

• If two computers in different rooms are connected together with long RS-232 wiring, ground loop problems tend to arise. Ground loops in Ethernet networks can make networks unable to operate properly and other annoying ground loop problems may be apparent. Thin Ethernet uses a coaxial cable which goes from computer to another. That cable should be grounded from one end for safety reasons and is electrically isolated from the computers at the Ethernet card.
  
  To avoid these kinds of problems, connectors which have plastic isolation over them may be installed or a plastic isolation could be installed around them. However, you must make sure that no metal connectors or broken cable connectors touch the metal wiring; otherwise a short circuit will be formed.