As a sort of transformer, a current transformer (CT) is used to increase or decrease an alternating current (AC). With respect to the current in its primary, it generates a secondary current that is equal in size.
Instrument transformers include voltage transformers, potential transformers, and current transformers. Instrument transformers reduce the huge voltage or current values to smaller, standardised values that are simple for measurement devices and safety relays to manage.
The primary system’s high voltage is isolated from measurement or protection circuits by the instrument transformers. A current transformer produces a secondary current that is precisely inversely proportional to the source current. The primary circuit experiences very little load from the current transformer.
The power system’s current-sensing components, or current transformers, are employed at generating stations, electrical substations, and in the distribution of electric power to commercial and industrial facilities. Current Transformers is the abbreviation for them.
They are the tools used to gauge the current flowing through a circuit. Because the circuit’s current is substantially higher than the relay can manage, CTs are required. In order to connect to the relay, CTs reduce the current to a low level that is safe.
The connecting component between the power system and all measurement equipment, such as protective relays, is the current transformer. In order to be used by metres, protective relays, metres, and monitoring equipment, CTs actually decrease the value of the main current to a notional secondary level.
The guarantee of a relay class transformer is that it won’t saturate at 20 times the rated current and will be accurate to within +/- 10%. Because of this, a metre can
The Global Current Transformers Relay Market accounted for $XX Billion in 2021 and is anticipated to reach $XX Billion by 2030, registering a CAGR of XX% from 2022 to 2030.
P&B is happy to announce the launch of many new Low Power Passive Current Transformers that are compatible with its well-known Motorvision, MicroMotor, and Primacon Protection Relays.
The new CT series has been introduced to replace traditional ring-type, solid iron-core transformers with 1A and 5A secondaries after a successful testing campaign. Larger transformers for low currents, such as 20-100A, are frequently used.
The new low power type is perfect for 415V type starters in withdrawable buckets found in tiered motor control centres since it has a significantly reduced footprint.
The P&B Hall Effect Sensor (HES) gadget, which needs a continuous power supply connection to operate, is likewise expected to be replaced by the LPCT.
On a motor starter that had been retrofitted at a cement plant, the new CTs were mounted for field testing. In order to install a P&B MicroMotor, an MTE IPC Protection Relay had to be removed and replaced in the same aperture.
The circuit has a fan drive, thus there is a significant amount of inrush current and a lengthy run-up period. The motor has a 33A max load current, but as can be seen from the video, a 22A normal loading. 50A CTs were installed. Due to spill current at first, the drive was vulnerable to erroneous earth fault trips during startup.
It was discovered that the original CTs were only 2x FLC, or 1.2x 50A, metering class rated, and saturated. As a result, the protective relay was unable to detect an overload or complete inrush current. As a result, the thermal capacity modelling was flawed, which had serious consequences for the thermal protection.
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