Shunt Reactor

People has been talking about the evil artifacts, such as, noises the active regulation brings, for example, those using a toroidal transformer with a motorized carbon brush, or even relays to switch to multiple taps in the transformer, to adjust the voltage when there are elevated mains voltage or brown-outs. Or, some audiophile just despises in-line or in-series regulators, saying that they choke the sound of their system, or restricts the dynamics  

So, is there a more elegant way of regulation other than the active way? Is there a way to regulate with passive components? Is there a shunt type of regulation device that can help with regulation? When it comes to transformer, or anything with a core and wire, ask us! 

Well, there is! And, it is called Shunt Reactor! 

Shunt reactor is used in industrial applications, more than home environment, where it is an absorber of reactive power to increase the efficiency of energy transmission, or to compensate (or consume) the reactive power generated by capacitive loads line capacitance - Ferranti effect). 

An inductive load consumes reactive power. A capacitive load generates reactive power. We have too MANY capacitive loads connected to our power line right now, especially with high power amplifiers that uses a lot of capacitors. Even an OPEN POWER LINE generates reactive power. 

The shunt reactor is normally connected permanently to the power line, or sometimes are switchable, or adjustable (VSR - variable shunt reactor) to cater for different daily-hour power draws or seasonal dips and peaks of power draw. 

In layman terms, shunt reactor automatically stabilize the voltage levels. minimize over-voltages. 

Usually the shunt reactor is permanently connected, or switched by a circuit-breaker (circuit-break is required ***important***). Several shunt reactors with different can be connected in parallel, or switched in and out to adapt to different power line conditions. 

A simple connection diagram of the shunt reactor is as above - across the live and neutral lines. For balance power, you will need two units of them to work in tandem. 

WARNING: It is dangerous and LETHAL mains / live AC voltages you are working on. Do it at your own risk. It is for qualified electrician only. WARNING. 

What consists of a good shunt reactor design? 

• Air-gapped core - constant impedance, reduce loss, avoid saturation, promotes linear energizing, and minimize remanent flux in the core (flatter hysteresis B-H curve, lower inrush current) 
• High inductance - high energy storage and resistance to changes 
• Low DCR or thick wire gauge - quick charge and discharge
• High grade core - minimize power loss, lower vibration and noise  

A shunt reactor may look like a transformer, but it is intended to consume or compensate reactive power, where as transformer is to convert one voltage to another, or one impedance to another. Shunt reactor has only one winding. Transformer has 2, and above for the conversion. 

Since it is switched on all the time, losses becomes important to avoid high electricity bill and heat. What are the major losses in a shunt reactor?

• Copper losses in the winding - wire 
• Core loss - iron core loss 
• Eddy current losses

Therefore, it is critical to minimize losses, and have a good shunt reactor design for better reactive power compensation / voltage regulation. 

Now, are you ready to DIY a shunt reactor device and use it in your home environment? 

J&K Audio Design
2/5/2020