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Current transformer shapes and sizes vary depending on the end-user or switch gear manufacturer. Low-voltage single ratio metering current transformers are either a ring type or plastic molded case. Split-core current transformers either have a two-part core or a core with a removable section.
A current transformer (CT) is a series connected measurement device designed to provide a current in its secondary coil proportional to the current flowing in its primary. Current transformers are commonly used in metering and protective relays in the electrical power industry.
Current transformers used in metering equipment for three-phase 400 ampere electricity supply SF 6 110 kV current transformer TGFM series, Russia. Current transformers (CT) are a series-connected type of instrument transformer. They are designed to present negligible load to the supply being measured and have an accurate current ratio and phase ...
The ratio of the voltage bases on either side of a transformer is selected to be the same as the ratio of the transformer voltage ratings. With these two rules, a per-unit impedance remains unchanged when referred from one side of a transformer to the other. This allows the ideal transformer to be eliminated from a transformer model.
The transformer ratio arm bridge or TRA bridge is a type of bridge circuit for measuring electronic components, using a.c. It can be designed to work in terms of either impedance or admittance . It can be used on resistors, capacitors and inductors, measuring minor as well as major terms, e.g. series resistance in capacitors.
Assuming the desired voltage is the same on the two and three phase sides, the Scott-T transformer connection (shown right) consists of a centre-tapped 1:1 ratio main transformer, T1, and a √ 3 /2(≈86.6%) ratio teaser transformer, T2. The centre-tapped side of T1 is connected between two of the phases on the three-phase side.
Darlington gives an equivalent transform that can eliminate an ideal transformer altogether. This technique requires that the transformer is next to (or capable of being moved next to) an "L" network of same-kind impedances. The transform in all variants results in the "L" network facing the opposite way, that is, topologically mirrored. [2]
The ferroresonant transformer, ferroresonant regulator or constant-voltage transformer is a type of saturating transformer used as a voltage regulator. These transformers use a tank circuit composed of a high-voltage resonant winding and a capacitor to produce a nearly constant average output voltage with a varying input current or varying load.