Generally any equipment will get damaged due to 3 primary reasons.
- Lightning or surges
- Temporary over voltages.
First 2 reasons are taken care of in design and considered as per worst case scenario.
However safeguards for temporary over voltage are generally not taken, certainly not considered as per worst case scenario.
In secondary side of LT transformer , worst case scenario is 440V in single phase.
It happens more often than expected.
Reasons for 440V coming in your supply
- Neutral open condition
- Double phasing
Causes of neutral open.
- Uneven load distribution
- Loose wiring.
- Accidental breakage
- Maintenance work errors
Causes of double phasing
- Trees falling on overhead wires
- Touching of overhead wires running through trees.
Majority of projects are located outside of city limits due to roof space constraints and industry requirements. Such scenarios are very common
Not one of the available solar inverter can handle a continuous over voltage of the above nature and will get damaged resulting in down time.
There is strong need of safeguard against such issue in design stage itself so that such issues can be tackled with min losses.
To illustrate, if there is short circuit or lighting strike, the system is designed to handle it. However for continuous over voltage there is not a single solution that can be offered.
There is infact no solution incorporated for 440V in single phase. Most of integrators rely on the inverters capacity of handling voltage fluctuation, and they will definitely get damaged in such a situation.
This is where it is recommended to take cognizance of potential problem that can be taken care in design stage itself.
We specialise in this area i.e. Neutral open and double phasing protection.
You can see our website www.microsystemservices.com for details on how we can add value to solar field.
Our appliances are getting smarter by the day. Its a good thing that many companies are energy conscious and are making their appliance even more energy efficient. In India most of home appliance are now made compulsory to have 5 star energy ratings, especially cooling appliances like ACs , refrigerators.
The TV ads are now flooded with ads talking about inverter based ACs, refrigerators. This is great news for energy conservation. However there is rider to all this. These units are susceptible to damages because of power fluctuations.
A traditional circuit consisted of a step down transformer which converted 230V AC to 24V AC which was then fed to bridge rectifier. The rectifier then converted the AC to DC and then it was distributed to the internal circuits with regulator and other component. Even if the voltage increased dramatically the secondary side would experience a relatively low surge on voltage. Prolonged exposure to voltages might have caused damages to internal circuits. In short these circuits were relatively very sturdy in voltage fluctuations.
However transformer has losses. It dissipates a lot of energy in the form of heat. Even in best cases the efficiency possibly didn’t not go beyond 87%, which was problem. Transfomer is bulky. Higher powered (kVA) machines would require a bigger transformer and as result were heavy too.
What we call inverter technology today , consist of PWM inverters and SMPS based circuits, may be even more advanced. These units have done away with conventional transformer based circuit and in effect increased the efficiency. They are also light weight , very compact and dissipate less energy as heat. They also come in attractive housings
However the flip side is that these circuits are now directly exposed to raw power. This is where the new problems have come up. These circuits are having 20% tolerance to voltage fluctuations. This would mean 180V on lower side and 280V on higher side. Seems ok doesn’t it? Wrong!!!
In developing and underdeveloped countries the power conditions are not so good and voltage frequently goes beyond 350V. This is a curse for these inverter based appliances, which get damaged more frequently than their predecessors.
These circuits are not inherently designed for such conditions and since units are manufactured considering global markets which include EU and US. Many white goods brands have made their foray in a new market only to have marred their reputation by service issues. We have many brands making their disappearing act after blitzkrieg of sales and ads.
One can attribute a serious contribution of such factors on making and breaking of brand in Indian conditions. There is probably two options here, either improve the tolerance of the internal circuits or protect the units externally by use of some protection equipment.
Do let us know what you think.
Author: Amit Manjrekar
(Click the image to learn more about him.)