MSS

Home » Posts tagged 'Over-voltage' (Page 2)

Tag Archives: Over-voltage

Advertisements

Loss to appliance manufacturers due to voltage fluctuation problems.


How often has this happen to you… You buy a brand new Plasma TV , Refrigerator, washing machine etc. just to find that it stops working with in the warranty period.

You call up the vendor and ask for replacement / repair of that equipment.  Have you considered that the quality of power at you house may be bad?  Even if you knew, would you acknowledge to the vendor?

Probably not!!! because you want a free service. Thats precisely what happens when any equipment fails. Equipment vendor is in a soup!!!

Power conditions are not good at all places. Voltage fluctuations are not something you can observe, not with out a voltage recorder definitely. But that wont be feasible at all times.

Effects of  voltage fluctuations are not understood until a very large catastrophe occurs and appliances are damaged.

Such a case has happen even in Metropolitan cities like Mumbai. There was a electrical fault at main distribution board of the house of very distinguished business person, wherein the neutral wire was burnt. This cause the voltage to shoot up to 440V ( this is called the neutral open condition).  At this voltage all the equipment in his house got damaged.  MCB/Fuse didnt react at all, and it will not. because MCB reacts to over current and not over voltage

He promptly called the appliance vendors and got the repairs done all free of cost as they were under warranty.

But here the manufacturer/ vendor had to bear the service cost. This includes salary for the day of the service technicians, changing of damaged components replacement of complete unit in some cases.

This cost is huge when you consider country-wide service.

We at MSS have developed , perfected and implemented device called OVCD for protection of equipments from power fluctuations.

We can help them reduce the events of such failures by more than 75%. This can improve the bottom line of the company.

Let us know in case of such problems at response@microsystemservices.com. We will be glad to be of any assistance.

Visit our Website for more details: http://www.microsystemservices.com

Linkedin Page: http://www.linkedin.com/company/304973

Blogsite: https://microsystemservices.wordpress.com/

Facebook page: http://www.facebook.com/pages/Micro-System-Services/130592683653306

Advertisements

Some Facts about overvoltage


Over voltage problems are the most frequent the most overlooked and neglected. Many times equipment failure, downtime, software and data corruption, are the result of a problematic supply of power.  There is also a common problem with describing power problems in a standard way. We have tried to list out some of the common facts about over voltage issues

  1. Overvoltage, and its destructive effects, are well known but are often not recognized or understood.
  2. Little is documented in terms of its magnitude and frequency.
  3. It is difficult to identify, due to its sporadic nature, and often comes and goes undetected.
  4. Because of all the above, its existence is sometimes denied.
  5. Equipment failures due to overvoltage are often misperceived as defective equipment.
  6.  Power companies do not deny its existence; but they do not publish or otherwise inform the users that it exists, or warn users of potential periods in which it may occur.
  7. Power fluctuations are also caused due to in–line equipment. Viz. Motor during its starting period draws heavy current due to which voltage drops causing imbalance and over voltage somewhere else.
  8. With very few exceptions, electrical power distribution systems are inadequate to provide voltage within acceptable limits to all users at all times.
  9. Power companies cannot prevent overvoltage because they can only react to its existence, usually in response to customer (user) complaints about failing appliances, etc.
  10. The time of response can vary widely (anywhere between one minute and weeks) depending on many variables in the distribution system.
  11. Overvoltage can occur at any time, due to many factors, but is most likely to occur during certain periods such as fast changing high load demands, as seen during severe cold weather periods.
  12. Power companies are mandated by law to provide service without overvoltage.
  13. Power companies are not held accountable by any regulation authority for overvoltage.
  14.  Power companies will sometimes reimburse damage costs due to overvoltage if proof is provided by the complainant.
  15.  Overvoltage can only be proved by the use of a voltage recorder.
  16.  Some power companies offer overvoltage insurance to users.
  17.  Over voltage events are misperceived to be equipment failures leading to their replacement with other brands that do not have overvoltage protection and essentially mask the effects of overvoltage which can lead to inevitable catastrophic failures.

Also see:

  1.  OVCD- Over Voltage Cut-off Device
  2. How does a Servo Controlled Voltage Stabilizer work?
  3. Product breakdown management
  4. Protect your Equipment from harmful power fluctuations..
  5. Give reliability to your UPS systems in high fluctuation areas. OVCD solves your servicing woes!!!
  6. Protect your electronics

Visit our website: www.microsystemservices.com

Our email us for more info at micross@microsystemservices.com

References:

  1. http://www.hvacovervoltage.com/info/Overvoltage_Wake_up_Call.pdf
  2.  http://www.hvacovervoltage.com/info/PowerProblems.pdf

OVCD- Over Voltage Cut-off Device


Only protection device for protection against neutral open and double phasing protection

DSCF 1046

Most of the equipments today are having power supply which can handle fluctuations between 170V to 270V.  Also a lot of equipments have built in over voltage protection. 

However there are accidental cases where trees fall on over head wires or accidentally neutral opens  and resulting fault causes voltage in single phase to shoot upto 440V. The in built over voltage protection of  any equipment is of no use , because they get damaged themselves. OVCD is protection device for protection against such problems of  neutral open or double phasing.

If you look at the pictures above you can see a typical distribution line problem. There is chance of wire sagging and over head wires touching each other . this can easily cause double phasing condition.

OVCD cuts off the supply to equipment whenever there is such a problem and connects the supply only when the voltage comes back to normal.

It effortlessly withstands voltage fluctuations up to 440 Volts and spikes up to 6000 Volts. It is programmed with a power-on delay of 3 seconds (configurable) for initial surges which are harmful to any other device.

 

Why should you consider using OVCD before your equipment?

1.No problems due to voltage fluctuation.
2.Zero downtime
3.Your equipment becomes more rugged
4.Less service calls = Increased profitability + Increased credibility.
5.Better perception of quality of your system in the minds of the customers
6.Increases the chances of repeat sales or referral sales.

USP:

Now you can install your equipment in the worst electrical conditions without being bothered about service calls.

Cost to company if your product breaks down.

Man power cost Rs 800 Travelling and per day costof service person
Production down time Rs 1000 Could cost upward dependingthe type of machine
Part replacement Rs 500 Could cost upward
Equipment decay Yes Reduction of life of equipment
Goodwill lost Yes Incalculable
Customer’s loss Yes Significant
Disturbing to business focus Yes Significant( both to customersand vendor)
Replacement of product Product cost Capital Loss

All figures in Indian rupees

Costs projected are indicative and may vary for product and services


Features

•Neutral open protection (Protection up to 440 volts)
•Withstands up to 6000V spikes
•Smart start
•Under/over voltage protection
•No wave form distortion
•Lightweight , transformer-less design
•Compact size.
How it works.

OVCD is connected at before the equipment in use.

Incoming current will first pass through OVCD then into the equipment. OVCD continuously monitors the line voltage.

Whenever the voltage is above or below the set voltage limits the OVCD simply cuts the voltage to the equipment thereby saving it from the line disturbance. It reacts within fraction of second to the disturbance. OVCD will withstand the voltage even as high as 440 Volts.It however does not stabilize the voltage as in the case of other devices in the same category like Stabilizer, CVTs.

When the voltage returns to normal , the OVCD resumes the supply to the equipment with short power-on delay of 3 seconds(configurable). This feature is called the Smart Start. It prevents the initial harmful transient that may damage the Equipment.

 

How is OVCD better than other power conditioning / protection products?

1.Superior protection
2.Occupies less space
3.Lightweight
4.Transformer less design
5.Portable.
Feature comparison with other devices in the same category
FEATURES  OVCD Servos  Stabilizer CVT Spike buster
Protection up to 440V

Yes

No No No No
Under voltage / Over voltage protection Yes No No No No
Protection from spikes Yes
No No Yes Yes
Protection from over load Yes
No No Yes No
Line indication Yes
No No No Yes
EMI /RFI filters Yes
No No No No
Waveform distortion No
No No Yes No
IC technology Yes
No No Yes No

Customized to suit your requirements.

We can customize the OVCD in following ways.

1.Voltage Settings( higher cut off, Lower cutoff voltages)
2.Power on delay
3.Input and output terminations
4.Enclosures
5.Configurations

 

 

End Use application

UPS AC drives Medical Equipments
Solar power plants Compressors CCTV system
Refrigeration equipments Control Panels Dish Satellite System

 

What is VA and Watts?


The terms VA (volt-amps) and watts are frequently used interchangeably when discussing the power consumption of an electronic device. This tendency is understandable when the total power consumption of the load is small and the value of VA and watts is nearly the same.

Nevertheless, it is important to understand the distinction between VA and watts in the event system power consumptions become very large or when numerous small loads are combined on a single source of power such as a UPS.

VA is an expression of “apparent power” and watts is an expression of “true power” in an AC circuit.

When the load is resistive, power dissipation in VA and watts will be the same.
See the following example

Figure A is a simple AC electrical circuit. In this circuit, the power source is 120 volts, and the load is a simple light bulb with 240 ohms of resistance.

The circuit current (I) can be calculated using Ohm’s Law by dividing the voltage (E) by the resistance (R).

I =  E/R
I =  120/240
I =  0.5 amps

In this case, a current of 0.5 amps will flow in the circuit.

The power (P) consumed by the light bulb may be calculated using one of these formulas: P = E x I or P = I2 R.

P = E x I P = I2 R
P = 120 x .5 or P = .52 x 240
P = 60 watts P = 60 watts

Things change, however, when the load becomes electronic. The constantly changing amplitude and polarity of AC power gives rise to reactive components in an electronic load.

There are two types of reactance – inductive and capacitive – and they are opposite in nature. Together with resistance, they represent an opposition to AC current flow called impedance.

VA and watts are no longer the same because circuits with impedance exhibit a characteristic called power factor (pf).
In AC circuits, VA is referred to as APPARENT power or what power appears to be flowing in the circuit. Watts are referred to as TRUE power or an indication of the power that is truly being dissipated by the load.

In addition to the power that reactive loads actually dissipate, a certain amount of power is absorbed by the reactive load and then once again released to the circuit. The power that is absorbed and then released again to the circuit is know as reactive power, and it is the difference between apparent power and true power.


The same AC circuit is powering a computer, which is a reactive load. The computer’s impedance is known to be 60 ohms. If we simply applied Ohm’s Law, the current flowing in the circuit would be equal to I=E/R or 2 amps. Again applying Ohm’s Law, the power consumed in the circuit would appear to be:

P = E x I
P = 120 x 2
P = 240VA.

Since the computer is a reactive load and not a resistive one, the power factor of the computer must be considered in order to determine the watts dissipated by the computer as follows:

P = E x I x pf
P = 120 x 2 x .65
P = 156 watts

The difference between the 240 VA apparent power and the 156 watts of true power is the reactive power or 84 VAR or volt-amps-reactive.

Most  products are rated in VA and also have a power factor rating that is prominently published as part of the product specification. In many cases, UPS power factors are designed to approximate computer power factors. In the example above, a 350 VA UPS with a power factor of .65 would deliver 227 watts, which would satisfactorily power the computer in question with about 72 watts to spare.
At low power levels, the differences between VA and watts are often slight. However, understanding the difference between VA and watts at higher power levels is very important to make sure the power protection device is compatible with the load

Also see

Protect you Laptop and note book against power fluctuations

Six power viruses

Understanding UPS made simple

Protect your electronics

Visit our website: www.microsystemservices.com

Give reliability to your UPS systems in high fluctuation areas. OVCD solves your servicing woes!!!


Micro Systems Services has successfully developed one of the most powerful and unique protection devices – simply called the OVCD–Over Voltage Cutoff Device.

Features :

  • Protection up to 440 volts( neutral open protection)
  • Withstand up to 6000v spikes
  • Smart start( power on delay)
  • Under/over voltage protection
  • Over load protection (optional)
  • High performance EMI/RFI filters (optional)
  • No wave form distortion
  • Line monitoring indication
  • Single phase preventor ( for 3 phase systems)
  • Phase reversal protection( for 3 phase systems)

How it works :
OVCD is connected at before the equipment in use. Incoming current will first pass through OVCD then into the equipment. OVCD continuously monitors the line voltage. Whenever the voltage is above or below the set voltage limits the OVCD simply cuts the voltage to the equipment thereby saving it from the line disturbance. It reacts within fraction of second to the disturbance.

The main feature is that OVCD is the only protection device which give nuetral open protection. i.e OVCD can withstand the voltage even as high as 440 Volts.
Most of the equipments will burn or get damaged at such voltages.

It however does not stabilize the voltage as in the case of other devices in the same category like Stabilizer, CVTs.

When the voltage returns to normal , the OVCD resumes the supply to the equipment with short power-on delay of 3 seconds(configurable). This feature is called the Smart Start. It prevents the initial harmful transient that may damage the Equipment.

Our product is used by significant number of MNCs in India like Emerson Network Power, Numeric systems, Delta Energy, DB Power, Asia Powercom , Techser and many more.

Our product has helped them to reduce the no. of events of product breakdowns by more than 75% and thereby reduce their operating cost.

We will be glad to provide you a sample test device and provide you with further information you may require on this unique product.

We can even customize the product to suit your requirements

Mail us at sales@microsystemservices.com for more queries.

Protect your electronics


A white paper on power problems


power outages- just a tip of iceberg

Background

The availability of business systems is significantly impacted by AC mains power quality. The degree to which power quality affects business systems depends on many factors, which include:

1. The quality of the electrical power

2. The downtime caused by factors unrelated to power

3. The ability of the business systems to recover from power problems

These factors vary greatly from site to site and from business to business and therefore it is inappropriate to make general statements regarding the impact of power on business process availability. Nevertheless, it is possible to take into account the specific issues of a site and a business and determine the quantitative effect of power problems on business operation

What constitutes a power problem?

AC power is imperfect. All AC power exhibits defects almost continuously including harmonic distortion, sags, swells, RF noise etc. Common citations regarding power quality and the frequency of power problems can be highly misleading because they often include power defects that do not affect information equipment. For a meaningful discussion of the effect of power problems on information equipment, a power problem must be defined as a condition where the AC power does not meet the necessary and sufficient conditions required to provide equipment operation. The generally accepted definition of necessary and sufficient power quality is the magnitude and duration of power problems which are likely to affect information equipment.


The Electric Power Distribution System

For purposes of understanding the distribution of Electrical Power, the system is typically separated into the following four levels:

Distribution Level Equipment

Bulk Power                             —          Power Plants

Area Power                             —          High Voltage lines

Distribution Network              —          Neighborhood power lines

Utilization Equipment             —          Building wiring

A failure at any of these levels can lead to a failure of equipment operation at the user site.

Bulk Power

Bulk Power is defined as a composite of the Generating Stations and the very high voltage transmission network. Problems with Bulk power affect the largest number of users. These problems are caused by

1. fuel shortages

2. human error

3. plant shutdowns

4. planned conservation

5. earthquakes

The statistics for Bulk Power availability vary widely. For example, on a small island Bulk Power may be a major contributor to down time. In Western Europe, the USA and Japan, the Bulk Power system is highly fault tolerant and a Bulk Power loss may occur only once every ten years or less.

Area Power

Area Power is defined as the transformer stations and substations supplying a given area.

Problems with Area power affect large blocks of people such as entire towns or cities. These problems are caused by:

1. equipment failure/wear out

2. overloads

3. weather

4. earthquakes

The statistics for Area Power availability vary widely. For example, some countries routinely employ interconnected stations with fail over capability while others employ a single path system. Systems with fail  over capability provide a much lower mean time to repair and hence higher availability.

Distribution Network

The Distribution Network is the local network of wiring which feeds buildings. This wiring typically follows streets and operates in the range of 5kV to 30kV and includes the transformers at the users site, which convert the power to the final utilization voltage. For many sites distribution is the primary cause of power problems. The distribution network is highly complex and exposed to many factors which can cause a power problem, including:

1. trees

2. wind

3. lightning

4. vehicular accidents

5. overloads

6. animals

7. construction accidents

9. earthquakes

The statistics for power problems in Distribution Networks are most strongly affected by local weather. In systems where Distribution wiring is underground these affects are reduced dramatically. In some cases, a significant degree of fail over redundancy is designed into the local distribution system, which reduces mean time, to repair and therefore increases availability.

Utilization System

The Utilization System consists of building wiring, circuit breakers, and internal building transformers. Power problems arising in the customer’s Utilization System are mainly independent of the geographic location of the site and are caused by factors that are typically in the control of the customer, including:

1. overloads

2. construction accidents

3. scheduled electrical work

4. electrician errors

5. heavy equipment startup

6. poor wiring connections

The statistics for power problems in Utilization Systems are most strongly affected by the existence of construction or wiring changes in the building, the nature of the business (industrial vs. knowledge workers) and the age of the building and wiring. In situations where the quality of the power supplied by the Utility Company is high,  power downtime may be dominated by Utilization System problems within the customer’s own facility.

Power protection devices

Power protection devices have traditionally fit neatly into one of two categories; those that alter, change, or otherwise control the character of electricity and those that provide an alternate or secondary source of power in the event of the failure of the primary

source. Products in the first group include surge protectors, filters, voltage regulator, power conditioners, and others. The amount of  protection varies from device to device. The operational requirements of LAN systems along with an emphasis on protecting data, software, and processes have created a significant level of interest in the uninterruptible power supply (UPS) products that comprise the second group. While it is possible for a UPS to also function as a power conditioner, such  capabilities cannot automatically be assumed. Indeed, along with the rapid growth in the number of UPS suppliers, the industry has seen the distinction between a UPS and a power conditioner become too poorly defined.

Fictional Concepts

The best place to start is by highlighting several of the most common misconceptions concerning UPS products.

These include:

A UPS provides total power conditioning. · For total power conditioning, an on-line UPS (as opposed to a standby design) must be used.· Standby UPS systems are undesirable because they only become active when power is lost.

Reality

Much has been said and written in the battle between different UPS technologies. It’s important to recognize that today, most UPSs are used in applications where the system is powered by a switch mode power supply. These power supplies make computer systems very tolerant of both voltage variations and short duration (5-20 msec) power losses.

The fact is that systems powered by switch mode supplies (and that’s most systems today) are perfectly compatible with standby UPS designs. Equally inaccurate is the assumption that because of its inverter design, an on-line  UPS provides superior power  conditioning to a standby UPS.

It is true that on-line UPS systems provide excellent normal mode protection (between line and neutral). Normal mode protection, however, is only one part of the power-conditioning picture  The switch mode supply is a significant improvement in electronic system design for a number of reasons. Not only does it make system more tolerant to voltage variations, but it is also smaller, lighter, more efficient, and quite a bit cheaper to produce.

All these advantages come with a price tag, however. The predecessor to the switch mode supply was the linear supply. It was characterized by a step-down isolation transformer on the input side. Elimination of the transformer in switch mode designs accounts for most of the physical and economic advantages.

However, it also results in a distinct operation disadvantage. That is the loss of common mode (neutral to ground) noise immunity for the system. Modern microprocessor system use electrical ground as a signal reference when making logic transitions and for the proper exchange of data between systems and peripherals.

For reliable operation, ultra-quiet ground reference is a necessity. Common mode  disturbances disrupt this clean signal reference. Such disturbances can only be eliminated with an isolation transformer. It is important to recognize that a UPS – any UPS – should include an isolation transformer in it output circuit. Without it, the UPS cannot qualify as a power conditioner because it will not be capable of protecting the attached  computer system from common mode noise.

There is a proliferation of UPS systems available in the marketplace that do not contain all the elements necessary to provide complete protection to the sensitive electronic load. This is true for both on-line as well as standby designs. Example abound of both types of UPS designs that fail to incorporate an isolation transformer as the final stage of their construction .

%d bloggers like this: