Desperate - Need HELP !!! Issue with voltage fluctuation in Bangalore

[kanwar]

Varistor is always placed across line and neutral path and normally has a fuse in series with mains line path. Now during short duration peaks the varistor acts as a low impedance shunt which sinks the current through it from line to neutral or vice-versa. The absorbing capacity is rated in joules and during longer duration peaks that capacity is exceeded and results in varistor blowing up and equipment is not saved anymore. Normally the fuse blows when large current is shunted by varistor but it seldom happens. This bakes the varistor to death.

 

[rdksrk2013]

In case of sustained overvoltages probably the only protection is to use a servo stabilizer as others have suggested.

A normal stabilizer will only have cut out facility in case of undervoltage or overvoltage.

In case of a servo stabilizer it will have a toroidal transformer the tapping of which is adjusted to increase the voltage in an undervoltage situation and decrease the voltage by changing the tapping of the transformer in a overvoltage situation. This is accomplished with a servo mechanism.

To a certain extent of undervoltage or overvoltage situation the servo stabilizer will provide a constant voltage output irrespective of the input voltage within the set capability limits of the stabilizer.

Only cons is that a servo stabilizer is noisy when the voltage is fast changing(like a dip or power off and on situation) because it has to adjust the taps of the transformer and also it is slow in response.

But I doubt if it can withstand a 400 Volt situation. I do not have idea. Probably the servo stabilzer guy can confirm this.

 

[john_k_antony]

Thank you guys for all the great suggestions.

I do have a 3KV Audio grade Vertex stabilizer for HT room. But I bypassed my Emotiva Amps and connected them directly to the wall socket after the recommendation from Emotiva . Now after I told them what happened, they asked me to check the fuse and now they say that, its okay to connect the amp to a stabilizer, but NOT to one with a surge arrester. I was also told that the Vertex stabilizers "rob" some of the audio frequencies.

From now on, what ever be it, I will connect ALL my equipment through the Vertex 3KV Audio grade stabilizer. I am not much worried about the lost frequencies any more. I want peace of mind .

The V-Guard stabilizer that blew was connected between my APC BackPro 1KV UPS and the wall socket. APC USP is for my projector alone. Though APC has protection built-in, once the protection blows up, it takes more than a week to repair it. But for V-Guard, it is easier for me to fix it as in my situation, the MOV always fails and burns. As Kanwar rightly said, usually the MOV fails because its not a temporary high voltage surge, but a sustained one.

I am still considering using one of the following

1. Micro System Services | Power Protection | Homeguard.

This will cost me around 18K for 3 phase for 10KV load capacity with customized voltage cut off range of 190V-260V

OR

2. Sukam 16A Power Guard

This will cost me around 4K for 3 phase.

Thanks,
John.

 

[john_k_antony]

Varistor is always placed across line and neutral path and normally has a fuse in series with mains line path. Now during short duration peaks the varistor acts as a low impedance shunt which sinks the current through it from line to neutral or vice-versa. The absorbing capacity is rated in joules and during longer duration peaks that capacity is exceeded and results in varistor blowing up and equipment is not saved anymore. Normally the fuse blows when large current is shunted by varistor but it seldom happens. This bakes the varistor to death.

Kanwar,

Quick question. When the Varistor fails and blows, it shorts the current path and that results in tripping your MCB in the DB right?

Thanks,
John.

 

[Thad E Ginathom]

I do have a 3KV Audio grade Vertex stabilizer for HT room. But I bypassed my Emotiva Amps and connected them directly to the wall socket after the recommendation from Emotiva . Now after I told them what happened, they asked me to check the fuse and now they say that, its okay to connect the amp to a stabilizer, but NOT to one with a surge arrester. I was also told that the Vertex stabilizers "rob" some of the audio frequencies.

We should not (never ever never) listen to American/European/Japanese manufacturers about this sort of thing. Their idea of "dirty" power, brown-outs, dips and spikes, is nothing compared to Indian conditions, and they can have no idea what risks both people and equipment suffer here daily. Even the London Sound hifi repair guy, claiming that voltage is usually high in UK, and that this shortens the life of equipment, is only talking about a few volts.

UK is the only other country I can speak of with experience. Domestic wiring is never more than single phase. Power gets interrupted by storm damage, but there is not (at least in my experience) the same regular shorting and damage of three-phase cables/transformers in the street causing extra volts by the hundred. Just about all the urban street power supplies are safely underground. The main high-voltage danger there is lightening.

That is the kind of background against which manufacturers are advising that some precaution or other might affect the sound of their equipment, but they are talking about high odds against such a thing ever happening, not a daily danger.


~

 

[kanwar]

Kanwar,

Quick question. When the Varistor fails and blows, it shorts the current path and that results in tripping your MCB in the DB right?

Thanks,
John.

You got it right....

 

[gobble]

Varistor is always placed across line and neutral path and normally has a fuse in series with mains line path. Now during short duration peaks the varistor acts as a low impedance shunt which sinks the current through it from line to neutral or vice-versa. The absorbing capacity is rated in joules and during longer duration peaks that capacity is exceeded and results in varistor blowing up and equipment is not saved anymore. Normally the fuse blows when large current is shunted by varistor but it seldom happens. This bakes the varistor to death.

Kanwar,

Quick question. When the Varistor fails and blows, it shorts the current path and that results in tripping your MCB in the DB right?

Thanks,
John.

Q1. So in normal operation varistor only conducts between L and N when very high current peaks pass it and other wise it does not conduct between the L and N path?
Q2. When it blows, it continues to conduct normal voltages between L+N and this shorts the current path?


Hope I understood that right?

~G0bble

 

[kanwar]

Varistors are rated at various voltage levels, when a particular voltage level exceeds, it starts conducting the current.
Normally when they blow they become open circuits or some times they do become short-circuits also if the current surge encountered was very high which exceeded the energy absorbing capacity of varistors.

Voltages are never conducted, only current is conducted.

 

[Thad E Ginathom]

If the current surge was high enough, I suppose we stop worrying about one protective component, because the whole unit is melting? Or the supply cable is.

My non-hifi worst was a burnt-out 3-phase mains supply cable. I think there was very low voltage, an AC machine was on, so it started to draw a very high current. Flames resulted somewhere underground in the garden. But no fuse or circuit breaker blew

 

[john_k_antony]

My non-hifi worst was a burnt-out 3-phase mains supply cable. I think there was very low voltage, an AC machine was on, so it started to draw a very high current. Flames resulted somewhere underground in the garden. But no fuse or circuit breaker blew

Oops Scary :O

 

[Raghav_K]

If the current surge was high enough, I suppose we stop worrying about one protective component, because the whole unit is melting? Or the supply cable is.

My non-hifi worst was a burnt-out 3-phase mains supply cable. I think there was very low voltage, an AC machine was on, so it started to draw a very high current. Flames resulted somewhere underground in the garden. But no fuse or circuit breaker blew

Wow... The stabilizer's low voltage cutoff didn't work?

 

[gobble]

I don't know how the MOV is setup inside the V-Guard. But It looks like three varistors are required for effective protection with a low Vn selected for the N+E connection. Here is a nice article that explains varistors beautifully and describes two common low cost ways of dealing with noise/spikes. Mains Filters - part 2 - Ferrites and VDRs

Does the Varistor + Ferrite constitute a Low Pass filter + RF filter?
How would a surge caused by a lightning strike look like at the power socket in the home? Will it create a common mode spike or a differential mode spike? Will the above combination block it completely?
What is the mechanism for low and high voltage cut-off in most popular consumer devices that claim to have the feature? The ones that we reset with a button or the automatic ones?

This may look OT, but some knowledge will help choose the right device if not angling for a Servo-Stab or other CVT.

~G0bble

 

[Thad E Ginathom]

Wow... The stabilizer's low voltage cutoff didn't work?

Nope. Nothing saved us. The lights went dim, the AC made funny noises and then ...nothing. Until our friendly EB engineer rigged us a single phase line from the pole, across the road, to the terrace, pending proper repairs.

How would a surge caused by a lightning strike look like at the power socket in the home?

A bit like a bomb?

But seriously, you are right: we need to know what protects us, and what doesn't.

 

[john_k_antony]

Planning to check out the 3-Phase Voltage Guard from Sollatek.

This is the priduct I am interested in - AVS-303

http://www.sollatek.com/pdf/Catalogues-Brochures/AVS 3 phase brochure 09.pdf

Sollatek has service center in Banglore and they also offer onsite service for their product. I am looking for a 10KV capacity / phase and the unit cost is around 15k. Talked to their technical rep today. Will explore more on this unit and might go for this mainly because of the onsite service option.

Let me know your comments.

Thanks,
John.

 

[jsmithe]

Planning to check out the 3-Phase Voltage Guard from Sollatek.

This is the priduct I am interested in - AVS-303

http://www.sollatek.com/pdf/Catalogues-Brochures/AVS 3 phase brochure 09.pdf

Sollatek has service center in Banglore and they also offer onsite service for their product. I am looking for a 10KV capacity / phase and the unit cost is around 15k. Talked to their technical rep today. Will explore more on this unit and might go for this mainly because of the onsite service option.

Let me know your comments.

Thanks,
John.

These only go as far as 300V for Overvoltage cutoff and 150V for Undervoltage? Wouldn't that be an issue if you are facing sustained 320V overvoltage?

 

[Tanoj]

This is Just a Auto Power off switch to turn off the power if there is fluctuation, or if the voltage crosses the lower or upper limit set, Time delay and surge protector.

Check for more options

Regards

Tanoj

 

[Raghav_K]

Wonder if it would be a better idea to have the whole home power coming through a 3phase servo stabilizer, excluding ac probably... No idea how much that would cost though...

 

[john_k_antony]

Whole house with Servo stabilizer will be an over kill. I think its not required for me.

I do have stabilizers for the all the lighting and appliances in my home. I also have a Vertex 3KV stabilizer for all the HT equipment. I do not need any power conditioning.

Now I just need an auto cut off device that shuts off power during a fluctuation and resume power after 30 seconds after the power is restored.

Regarding Sollatek, the one I am looking for is a 3-Phase solution and it can withstand upto 440V according to their technical team. The single phase units can withstand a maximum voltage of 320v continuous.

Thanks,
John.

 

[Thad E Ginathom]

I am not sure that a servo-stabiliser reacts fast enough to a major spike (experts?). It would be a great thing to have, but even then more might be needed.

 

[john_k_antony]

I am not sure that a servo-stabiliser reacts fast enough to a major spike (experts?). It would be a great thing to have, but even then more might be needed.

Even I fear the same about servo.