…isolating what matters!
How does an Isolation Transformer solve this problem?
Essentially by installing an isolation transformer you will creating your own substation and by the very inherent design of the transformer there is no physical contact between the input and output sides, technically referred as Galvanic Isolation.
This is the same device typically used in boats where there is no physical earth and you have to supply noiseless power to power devices on board.
HOW ISOLATION TRANSFORMERS WORK
Most transformers are used for voltage stepping, to raise or lower the secondary voltage as compared to the primary voltage. Isolation transformers differ, in that their primary purpose isn’t voltage stepping, but rather isolation. While they may step the voltage up or down, that isn’t their main usage.
The design and construction of isolation transformers differs from that of stepping transformers in one primary way; the inclusion of faraday shields between the primary and secondary. There are two of these shields, a primary one and a secondary one. The primary shield is normally grounded to the ground on the incoming current to the primary, while the secondary shield is normally grounded to the device or system’s ground.
By grounding these faraday shields, the transformer is able to ground out the spurious noise signals, while allowing the signal to travel through the transformer, on to the device’s circuitry. Essentially, the isolation transformer acts as three capacitors, one for the input one for the output and a common one to ground. This “filters” some of the noise to ground.
TRANSFORMER ISOLATION AND GROUND
Due to the circuit isolation that any transformer provides, it is possible to derive a new ground on the secondary side of the transformer. Typically, electric power companies connect neutral to ground at some point, meaning that ground really isn’t ground. On the secondary side of the transformer, it is possible to connect ground to earth ground, ensuring a good ground for the elimination of the noise “captured” by the faraday shield.
If the transformer is designed to do so, the ground can also be established at some other voltage than zero. This provides the possibility of establishing a ground at a higher voltage, referred to as “lifting the ground,” so that the noise is “swallowed up” into the ground voltage. The difference in ground potential between the primary and secondary in these cases makes it harder for spurious noise to transition from one side of the transformer to the other. This is most effective when the noise is contained in a more electronegitively charged primary circuit, and the secondary is more electropositively charged.
Let’s go back to the power companies tying the neutral to ground for a moment at substation. While this typically reads as zero volts, there is the potential that the neutral leg could have a high voltage potential, even as high as 20 KV. While the potential between the neutral leg and the ground leg would be zero, the potential between the neutral leg or ground and true earth ground could be that full 20 KV.
ISOLATION TRANSFORMERS SPECIFICATIONS
Isolation transformers are extremely effective for reducing high frequency common mode noise. However, they have very little effect on low frequency or differential noise. Since isolation transformers are commonly used for noise reduction, it is normal to rate them by their attenuation. This is the amount of noise that they are capable of removing.
Attenuation is always rated in dB (decibels). This can be confusing, because the amount of noise eliminated depends largely upon the amount of noise that exists.
Isolation transformers are not as effective in dealing with transients, such as voltage spikes. If the transients are in differential mode (on the neutral leg) they will pass directly through the transformer with no attenuation.
A typical scenario at studio
This can be very, very handy when folks bring in guitar amps or synth racks with serious internal problems, and lifting the safety ground is the only way to get the noise down. It’s not a good long-term fix for anything but it can be a very handy quick fix for problems like this when there is no time to fix them properly. Here an isolated power supply dedicated and reserved for such small applications would be life saver.
|Secondary Voltage (1:1)||230V|
|Impedance||Less than 4%|
|Power Factor considered||0.8|
|Dielectric Strength||2.5KV for 1 minute|
|Noise Attenuation||90db / 115db|
|Efficiency||More than 98%|
|Operating Temperature||0-50 degree|
|IS Standards||IS 9815|