VPI type of transformer is made with minimum flammable material as insulation of windings. The windings of this transformer are made in foil or strip in a continuous layer. But, for higher voltages the winding is made of disks that are connected in series or parallel as per power rating with respect to
voltage level. The insulation of the winding is void free impregnation that is made with class H polyester resin. Moisture Ingress Protection is high and it never gets affected by moisture. This type of transformer is available with insulation grade F(155 C) and H(180 C).

Advantages:

• High mechanical strength.
• Void free insulation.
• No temperature fluctuation.
• Easy maintenance.
• Less prone to fire hazard.

• Control Transformers are useful where the available voltage must be changed to accommodate the voltage required by the load.
• For many electrical circuits, the National Electrical Code (NEC) requires a Separately derived neutral secondary connection provided by Delta Wye connected transformers.
• Transformers are manufactured in a variety of choices to meet many applications like Dry type transformers are offered encapsulated, ventilated or non ventilated, 600 Volt Class, isolation type, single and three phase, Indoor and outdoor models are an option.

An isolation transformer is a transformer used to transfer electrical power from a source of alternating current (AC) power to some equipment or device while isolating the powered device from the power source, usually for safety reasons.

Uses:

• Medical equipment
• Telecommunication equipment
• Remote control equipment
• CNC machines

• Potential transformer is a voltage step down transformer Potential Transformer which reduces the voltage of a high voltage circuit to a lower level for the purpose of measurement.
• These are connected across or parallel to the line which is to be monitored.

• A choke is an inductor that is utilized to block high frequency i.e. Harmonics in a circuit while allowing lower frequencies to pass through.
• A choke (or line reactor) is a coil of wire around a magnetic core that creates a magnetic field when current flows  through it. This magnetic field increases the impedance of the line and reduces the total harmonic content injected from the drive onto the facilities Electrical.

What is an AC Choke?

• AC Reactor Chokes are specially designed for lowering the cable lengths in those applications where the distance from drive to load exceeds 25 meters.
• Installed on the variable frequency drive, either on its input (line) or output (load) side, these reactor chokes ensure impedance matching, di dt and harmonic mitigation. AC line reactors are added to the input of the drive and placed in series with the incoming line.
• They help to mitigate harmonics and because they are between the line and the drive, they are able to act as a buffer for surges and other transients.

Specifications

• Detuning factor : 5% , 7%
• Rating : 5 KVAr , 10 KVAr , 20 KVAr , 25 KVAr , 50KVAr, 100 KVAr
• Tapping’s : As per request
• Rated Voltage : 380V to 1 KV
• Rated Frequency : 50/60 Hz.
• Linearity : 200%
• Ambient Temperature : 50 C
• Insulation Material : CU
• Temperature rise : 90 C
• Protection : IP 20/As per request
• Applicable Standard: IS 5553 1990

Features:

• Long functional life
• Safe to use
• Sturdy design
• High performance
• Ability to reduce the current and voltage
• Stresses on the input rectifier bridge Over voltage restriction
• Available in single and three phases
• Better protection of the drive
• Improvement of low frequency conduction emission and sensitivity

Applications:

• 3%, 5% & 7% Impedance
• 50 Hz to > 5 kHz VFD’s
• Line & Load applications
• Submersible pumps in oil well Process plants with output (load) chokes
• VFD’s Yasakawa , Mitsubishi, Siemens, Allan Bradley, Fuji, Danfoss , LG and Control Techniques

Advantages of AC Choke:

AC line reactors can be easily added in front of any drive since they are wired on the input lines. This can help reduce ripple voltage when the input voltage is unbalanced. Since the AC line reactor is located in front of the input rectifier, it builds a low pass filter with the capacitors located on the DC bus at the
output of the rectifier and the phase to phase capacitors included in the EMC filter. This provides protection for the input rectifier against overvoltage.

Our prudently designed DC Chokes are suitably utilized in industrial machinery power systems for filtering the power supply. These chokes are made sturdily by making use of optimum grade copper wires terminal blocks and electrical steel laminations. To ensure low power loss, th e laminations used in these chokes are electrical grade CRGO. This choke range maximizes the circuit inductance in the electric and electronic circuits.

What is an DC Choke?

DC link chokes are connected between the diodes and the DC bus and can be slightly less or slightly more effective at removing harmonics than AC line reactors depending on the order of harmonic being observed. DC link chokes are typically smaller than AC chokes and they Add the necessary impedance for harmonic reduction without a  drop in voltage. While the DC choke does not add any extra buffering from voltage surges seen by the rectifier, it will protect against current surges.

Features:

• Excellent power filtration
• Make sure no damage to input rectifiers from in rush current
• Improvise low frequency conduction emission
• Overload protection
• Reduce current voltage stress
• Excellent protection to motor drive
• Lowers harmonic distortion
• Compacted design

Applications:

• Power Electronic Systems
• Rectifier Modules
• Servo Drives
• DC Bus Systems
• Di / Dt Smoothening units
• AC Ripple Reduction Systems

When to use an AC or DC Choke and why?

A variable frequency drive (VFD), being a non linear load, is a source of harmonics on the power line. Harmonic current causes additional heating of the transformer and cabling to the VFD, which reduces the capacity of the
cable and transformer. An AC line reactor or DC link reactor (DC Choke) is used to mitigate the impact of harmonics in VFD applications. Prior to selecting an ac line reactor or a dc link reactor for mitigating the impact
of harmonics in VFD applications, it is prudent to carefully review the advantages and shortcomings of both and select the one that is better for that particular application.

• Current transformer (CT) is a type of transformer that is used to reduce or multiply an alternating current (AC).
• It produces a current in its secondary which is proportional to the current in its primary.