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In electronics testing and servicing, an isolation transformer is a 1:1 (under load) power transformer used for safety. Without it, exposed live metal in a device under test is at a hazardous voltage relative to grounded objects such as a heating radiator or oscilloscope ground lead (a particular hazard with some old vacuum-tube equipment with ...
English: A schematic diagram showing one solution to the problem of a ground loop between electronic components - insert an isolation transformer in the signal cable. A ground loop is an inadvertent electrical circuit or loop created by the ground wiring of electrical equipment. Ground loops are a major cause of hum and interference in audio ...
Single-pole circuit breakers feed 120 V circuits from one of the 120 V buses within the panel, or two-pole circuit breakers feed 240-volt circuits from both buses. 120 V circuits are the most common, and used to power NEMA 1 and NEMA 5 outlets, and most residential and light commercial direct-wired lighting circuits.
Isolation transformer Use a ground loop isolation transformer in the cable. [4] [5] This is considered the best solution, as it breaks the DC connection between components while passing the differential signal on the line. Even if one or both components are ungrounded, no noise will be introduced.
A 120:120 instrument isolation transformer showing two polarity marking conventions. Voltage transformers (VT), also called potential transformers (PT), are a parallel-connected type of instrument transformer. They are designed to present a negligible load to the supply being measured and have an accurate voltage ratio and phase relationship to ...
The primary winding of the transformer is connected to the high voltage or high current circuit, and the meter or relay is connected to the secondary circuit. Instrument transformers may also be used as an isolation transformer so that secondary quantities may be used in phase shifting without affecting other primary connected devices. [1]
This practice arose from the three-wire system used to supply both 120 volt and 240 volt loads. Because these listed appliances often have components that use either 120, or both 120 and 240 volts, there is often some current on the neutral wire. This differs from the protective grounding wire, which only carries current under fault conditions.
Transformers couple by magnetic flux. Except for the autotransformer, the primary and secondary windings of a transformer are not electrically connected to each other. The voltage difference that may safely be applied between windings without risk of breakdown (the isolation voltage) is specified in kilovolts by an industry standard.