I am reading in the SMA TL installation manual that the transformerless inverters don't have galvanic seperation. What does it mean?
Comments
Galvanic separation (or isolation) refers to the fact that the output power circuit is electrically and physically isolated from the input power circuit. Electrical isolation is accomplished using an isolation transformer. Physical isolation means that the output power wiring does not touch or connect to the input wiring.
It's used in inverter transformers;
to allow the output of a device to float relative to avoid potential ground loops
to increase the safety of a device, so that a person touching the live portion of the circuit will not have current flow through them to earth.
Just to give a quick overview about the background of related inverter technology here. The inverters may use;
the newer high-frequency transformers,
conventional low-frequency transformers, or
no transformer.
Instead of converting direct current directly to 120 or 240 volts AC, high-frequency transformers employ a computerized multi-step process that involves converting the power to high-frequency AC and then back to DC and then to the final AC output voltage.
Transformerless inverters, which boast lighter weight and higher efficiencies than their counterparts with transformers. Until 2005, NEC code required all solar electric systems to be negative grounded, an electrical configuration that interferes with the operation of transformerless inverters. The issue at stake currently is that there are concerns about having transformerless electrical systems feed into the public utility grid since the lack of galvanic isolation between the DC and AC circuits could allow the passage of dangerous DC faults to be transmitted to the AC side.
The new NEC code allows the use of ungrounded systems and the transformerless inverters.
Comments
Galvanic separation (or isolation) refers to the fact that the output power circuit is electrically and physically isolated from the input power circuit. Electrical isolation is accomplished using an isolation transformer. Physical isolation means that the output power wiring does not touch or connect to the input wiring.
It's used in inverter transformers;
Just to give a quick overview about the background of related inverter technology here. The inverters may use;
Transformerless inverters, which boast lighter weight and higher efficiencies than their counterparts with transformers. Until 2005, NEC code required all solar electric systems to be negative grounded, an electrical configuration that interferes with the operation of transformerless inverters. The issue at stake currently is that there are concerns about having transformerless electrical systems feed into the public utility grid since the lack of galvanic isolation between the DC and AC circuits could allow the passage of dangerous DC faults to be transmitted to the AC side.
The new NEC code allows the use of ungrounded systems and the transformerless inverters.