Overview, Type Selection and Installation Method of Open Current Transformer

The open current transformer is mainly used in the transformation project of power distribution system. It is easy to install. It can also be operated live without dismantling the primary bus. It does not affect the normal power consumption of customers, and saves manpower, material and financial resources for the transformation project of users. This series of current transformers can be used together with relay protection, measurement and metering devices.

Removable low-voltage current transformer, also known as open current transformer, is mainly used in the transformation project of distribution system of 0.66kv and below. It is easy to install, does not need to dismantle the primary bus, and can also be operated on line, does not affect the normal power consumption of customers, and saves manpower, material and financial resources for the transformation project of users. This series of current transformers can be used together with relay protection, measurement and metering devices.

Akh-0.66 series current transformer shell adopts imported polycarbonate injection molding with flame retardant and temperature resistance of 140 , the iron core is wound with oriented cold-rolled silicon steel strip, and the secondary conductor adopts high-strength electromagnetic enamelled wire. The product has novel structure, beautiful shape, convenient installation, small volume, light weight, high accuracy and large capacity.

analysis

In the process of actual use, customers always ask why the open current transformer makes noise during operation? Take the akh-0.66 K series open-ended transformer of ankerui as an example, let me tell you:

1. During the operation of the open transformer, if the wiring of the secondary outgoing lines S1 and S2 is unreliable (i.e. secondary open circuit), it will produce a sound. If it operates for a long time, it will produce a large open circuit voltage due to the saturation of the magnetic core, which will heat the iron core until the transformer is burned. Therefore, when the open transformer makes a sound during operation, first check whether the wiring of the secondary outgoing lines S1 and S2 of the transformer is firm and reliable.

2. When installing the open transformer, ensure that P1 of the upper housing corresponds to P1 of the lower housing on the same side, and P2 corresponds to P2 on the same side. The iron core of the open transformer must be paired up and down. After the unmatched iron core is installed, the contact surface will produce a gap. At this time, the transformer will make a sound when in use; Therefore, when the open transformer makes a sound during operation, check whether the same sides P1 and P2 of the upper and lower shells correspond.

3. When there are foreign matters on the upper and lower contact surfaces of the open transformer iron core, it will make a sound. Therefore, pay attention to the contact surface of the iron core during installation to ensure that it is clean and free of foreign matters.

Product introduction

Akh-0.66 series current transformer shell is made of flame-retardant imported polycarbonate injection molding, the iron core is made of oriented cold-rolled silicon steel strip, and the secondary conductor is made of high-strength electromagnetic enamelled wire. The product has novel structure, beautiful appearance, convenient installation, small volume, light weight, high accuracy and large capacity.

Specification and size

Technical indicators

Open ended CT primary current 100-6300a, secondary current 5A, 1A

Rated working voltage ac0.66kv (equivalent ac0.69kv, GB / t156-2007)

Rated frequency 50-60Hz

Power frequency withstand voltage 3000V / 1min 50Hz

It is used in places without direct invasion of rain and snow, serious pollution and violent vibration

Selection and installation method

Select the corresponding specification products according to the primary current, bus section and other parameters. The primary conductor passes through the window hole of the transformer. Open the flap and conduct secondary wiring through the wire pressing piece. After the secondary wiring is led out, the flap is reset. For measuring electric energy, the flip hole can be directly used to seal the lead print to prevent electricity theft.

The working current shall not exceed 1.1 times the rated value for a long time, and it is allowed to be used for a short time at 1.2 times the rated value for no more than 1h;

Select the rated current ratio according to the measured current, and generally select the rated current about 2 / 3 larger than the measured current;

Product polarity is expressed as: primary wiring marks P1 and P2, corresponding secondary wiring marks S1 and S2; S1 represents the homonymous end of P1 and S2 represents the homonymous end of P2;

The measuring instrument is connected to terminals S1 and S2. At this time, the total load of the connected circuit shall not exceed the rated load of the transformer. When the installation position of the instrument is far from the current transformer or the circuit load is large, the specification with secondary current of 1A shall be preferred;

Pay attention to select the transformer with matching window size according to the specification and number of busbar.

Current transformer is an instrument that converts a large current at the primary side into a small current at the secondary side according to the principle of electromagnetic induction. Current transformer is composed of closed core and winding. Its primary winding has few turns and is connected in series in the line of current to be measured.

The principle of current transformer is based on the principle of electromagnetic induction. Current transformer is composed of closed core and winding. Its primary winding has few turns and is connected in series in the line where the current needs to be measured, so it often flows all the current of the line. The secondary winding has many turns and is connected in series in the measuring instrument and protection circuit. When the current transformer is working, its secondary circuit is always closed, so the impedance of the series coil of the measuring instrument and protection circuit is very small, The working state of current transformer is close to short circuit.