Product breakdown management
Many Equipment manufacturers have sold their units all over India. They might be very successful in mass distribution, but with large sale comes the liability of servicing the faulty units.
Even a conservative 1% defect ratio over one lakh units sold would mean 1000 units all over India
For every faulty equipment there is huge cost on servicing.
This would consists of cost of service technician per day, his travelling cost, accommodation , cost of spares, replacement of parts
MSS has protection devices which can reduce 75% of incidents of product failure.
As the old saying goes ” Money saved is money earned”
This would translate into huge savings which directly affects the bottomline of the company.
This is what we do. We help equipment manufactures save money on product breakdown.
For more queries mail us at: micross@microsystemservices.com.
Or visit us at www.microsystemservices.com
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
Visit our website: www.microsystemservices.com
Reduce your electricity bills by using a high efficiency UPS systems
Did you know that difference of only 1 % in efficiency in Online UPS system can save more than 3 lakhs rupees per year?
An Online UPS is ON 24 hours of the day 365 days in a year, except in the case of a voluntary shutdown. It consumes electricity all the time.
So if you are using an online UPS system at your office you should seriously consider how much efficient your UPS is and how much you tend to lose out.
When making a buying decision for a UPS , companies generally look at intial cost of the system. But the Total cost of ownership is more often not calculated and ignored. Now a days there is increasing emphasis on reducing the costs in business process. Energy costs should also be taken into account.
TCO( total cost of Ownership) = Initial cost of UPS + Maintenance charges + Running charges.
The amount wasted due to inefficiency in 1-2 years can be equal to the cost of the UPS itself.!!!!!!
What is UPS efficiency?
Energy efficiency of a UPS can be expressed as the difference between the amount of energy that goes into a UPS vs. the amount of useful energy the comes out of the UPS to power your loads. In all UPS systems, some amount of energy is lost as heat when it passes through the internal components of the UPS (transformers, rectifiers, inverters etc.).
The less efficient the UPS is, the more heat it will reject. This means air conditioning energy costs are also lower by using a high efficiency UPS. It takes an extra 3,400 BTU per kW of heat lost by the UPS to maintain the room temperature. A typical air conditioner requires 0.3 kW of energy to generate 3,400 BTU of cooling. As a rule, the air conditioning costs equal 33 per cent of the of the kW costs of lost energy of the UPS. So air conditioning charges would increases as the heat dissipated by UPS increases.
So the equation above becomes
TCO( total cost of Ownership) = Initial cost of UPS + Maintenance charges + electricity consumption by UPS+ Air conditioning charges.
Cost savings from using a high efficiency UPS often equals the value of the UPS in as little as 3 to 5 years.
Just how much energy is lost between the input and output can be significant when you consider how much the wasted energy is costing. Energy efficiency advantages of as little as 1 percent between one UPS and another can translate into thousands to lakhs of rupees saved per year depending on the size of the UPS.
Let us take an example of 100kW UPS
90% efficiency would mean loss 10kW.
10 kW of lost energy may not seem like a lot of power, however, UPS loads operate continuously 365 days a year.
10 kW of used energy now equates to 87600 kWh of power wasted each year.( 24hours x 365days x 10 kWh)
1kWH equals to one unit of electricity.
With a meter rate of Rs. 6/unit, this equates to Rs. 5,25,600 of energy wasted by the UPS and an additional Rs 1,73,448 in extra energy costs just to cool the heat ejected by the UPS — resulting in a total of Rs. 6,99,048 in electricity wasted !
No matter what UPS system you select, there will be some energy lost between the utility and the output, but high efficiency UPS systems can dramatically limit the energy loss, resulting in substantial cost savings.
Consider the previous scenario.
What if the same UPS was 95% efficient as opposed to 90 % efficient losing only 5 kW of energy as heat. The difference in energy savings would be over Rs. 3,49,524 per year!!!!!!
How do you know if you are getting a high efficiency UPS?
When comparing the energy efficiency of UPS vendors, published efficiency specifications from UPS vendors may all seem very similar, leaving you to wonder whether there is any difference between manufacturers. The only way to ensure that a UPS vendor is giving you straight facts about efficiency is to demand a witness test on your specific UPS prior to shipment from the factory. As a customer you have the right to know.
An efficiency test is like test-driving a car to measure fuel efficiency. Just as cars get radically different mileage when driving on the highway vs. a windy mountain road, UPS efficiency also can change with the type of load it powers. Today almost all UPS power 100 per cent non-linear loads (computers, servers, motors and electronic equipment).
When most manufacturers test their UPS, they use linear loads, which are not representative of customers’ actual loads. This is very convenient for some manufacturers, as UPS efficiency will often be much higher when powering linear loads. Some manufacturers won’t show the customer the true energy consumption of the UPS when installed at their site. Only by insisting that manufacturers demonstrate efficiency with non-linear loads representative of real world environments can you be sure of the UPS true efficiency.
The second major factor to influence UPS efficiency is at what power level the efficiency is measured. Just like a car will have its best mileage operating at around 60 mph, most UPS typically will have their best efficiency operating at 50 per cent to 100 per cent load level. Again in the real world, most UPS systems operate at 25 per cent to 60 per cent of their nominal load — not fully loaded.
To determine accurate efficiency, the UPS should demonstrate efficiency at loads below 25-50 per cent where most UPSs will likely be operating, especially if operating in redundant configurations. Hardly any UPS systems run at 100% load and those that are in N+1 or 2(N+1) redundant configurations rarely exceed 30% load per module.
Only by testing your UPS under actual expected load levels (25-50 per cent in most cases).and simulating an actual load profile in your facility will you know the real efficiency of your UPS.
How much will a high efficiency UPS save you?
To calculate how much you will save using a high efficiency UPS, estimate your actual load and utility rate category. Calculate efficiency based on example given above
Protect your Equipment from harmful power fluctuations..
OVCD is the most powerful device of its kind. It can protect your equipment in the most extreme power conditions and protect it from line disturbance.
It can save your servicing costs by more than 75%
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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.
Some things to think about when buying a UPS system
Below are some general questions when buying a UPS system:
Off-line
An off-line unit would be the most basic UPS system as the load is supplied by raw mains until such times that the voltage or frequency would go outside the preset tolerance levels at which time the system would support the load via its battery. These units are primarily used for PC’s or servers but should not be used in an area were the local power supply is particularly unstable.
True online double conversion
True online double conversion UPS systems, due to the continual AC to DC followed by DC to AC conversion, provide a consistent quality of power. As the UPS output is independent of the mains input no matter what disturbances or fluctuations there may be on the mains supply there will always be a clean controlled output. This type of system is suitable for all applications were a high availability of supply is required.
Redundancy
Redundant systems are utilized in order to provide added resilience to further reduce the risk of a power failure. Multiple UPS systems are connected together sharing the load, this enables essential maintenance and repairs to be carried out on any of the connected modules without having to transfer the load to mains supply.
Scalability
Scalability is for instances when it is estimated that the load may increase in the future so the UPS system should be scaled up to match the demand. It is also used where the budget for the UPS requires that a smaller system can be purchased at the outset to suit the current load with additional modules
Communications
UPS systems have various options for communications such as volt free contacts for connection to the buildings BMS to network connectability enabling SNMP. It is best to decide on communication options from the outset so that the necessary cabling etc can be installed.
Contact Us
If you need any more information, or if we can help you in any way, then please contact us by sending us an email on sales@microsystemservices.com
Inverter-Battery buying tips and calculations
You must be having a hard time and may be even trying to get an inverter. But must be confused which inverter and battery to choose. Some may have bought them already but presently may not be sufficient to provide electric backup. So, I suggest you do some homework before buying or upgrading the inverter/battery.
Thumb rule is that you select inverter based on the power required and battery based on the backup time required.
Selecting Inverter:
Inverter rating (VA) must be greater than the total power required by the devices to be operated via inverter. So, first of all sum up the powers of all those devices. I have listed the power consumption value for some equipments below.
| Appliances | Power (Watts) |
| Laptop Computer / Digital Camera | 35-45 |
| 100W Light / 12″ Fan / 19″ Color TV | 100 |
| Computer / Printer / Fax | 300 |
After getting total powers in watt, you need to convert that to corresponding VA value; to compare with the inverter rating. conversion from watt to VA can be done using the equation below.
Power in VA = power in watt / power factor
power factor = 0.8
| Example: There is a 1 computer, 1 TV and 4 CFL lamps (5 watt each) then total power = 300+100+4×5 = 420 Watts. In VA that corresponds to 525 VA. So we need an inverter with rating greater than 525 VA . |
Selecting Battery:
For the battery selection the equation below summarizes all the points.
Battery Voltage x Battery AH rating = Required VA x Backup Time
Battery AH rating = Ampere-Hour rating of the battery
Backup Time in hours
We already have the Required VA as calulated from the total power required. Now we have to figure out ourselves the backup time required and decide to use 12 V or 24 V battery. Or we may combine batteries in series to sum up the voltage and get higher voltage.
After then we can calculate the AH rating and get a battery near that rating.
| Example: As for the previous case, Required VA = 525VA. If we require it for backup time of 6 hrs with 12V battery then battery AH rating = 525×6/12 = 262.5 AH. But if we use 24V battery then battery AH rating = 525×6/24 = 131.25 AH |
Also see:
How to a high efficiency UPS can save you more than 3 lakhs per year
Protect your equipments from high voltage fluctuations- video presentation
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Six Power Viruses
You’ve heard about the dangers of software viruses. But did you know that power viruses can do just as much damage to your system? And that a typical office experiences as many as 6,000 power viruses or more, every year?
Some of these power disturbances are obvious, some are almost unnoticeable, but they all cause problems that can seriously damage your productivity, from lost data and lock-ups to communications errors and hardware failures.
| Common-mode voltage problems Probably the most serious virus facing computer users today, common-mode voltage problems can cause unexplained data losses, glitches, system failures and “no trouble found” service calls. The only way to immunize against common-mode voltage is to install a power conditioner or UPS that has an isolation transformer output. |
| Electrical Noise This virus is spread by electrical neighbors such as electronic lighting ballasts, appliances, printers, photocopiers and even other computers. Over time, and in connection with low-voltage spikes, noise can wear away electrical components and cause them to fail for no apparent reason. |
| Voltage spikes and impulses Like electrical noise, this virus is also spread by equipment inside your facility. When elevators, motors or air conditioners stop and start, they can cause sudden large increases in voltage inside the electrical system. Other causes include electric utility switching and lightning strikes (which can cause transients so intense they literally “blow up” sensitive electronics). |
| Voltage regulation In the past, unregulated voltages wreaked havoc with linear power supplies, making it hard for computer-based equipment to function. Failures were common. But thanks to the switch-mode supplies used in today’s computers, today’s systems have developed their own immunity to voltage regulation viruses. (This immunity is a by-product of the same technology that makes switch mode supplies smaller and more economical.) |
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Blackouts |
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Backdoor disturbances Fiber optic connections are one means of protection, but if your system uses ordinary communications wiring and connections, you need to immunize it against this often unrecognized but very dangerous virus. |
Common electrical terms
Many a times, when we are deciding to buy a UPS or and electrical equipment , we are bombarded with a lot of technical Jargons . This is just glossary of common electrical terms in an attempt to De-mystify the Jargons. This will work just like an dictionary .. just technical one
Alternating current (AC): An electrical system in which voltage polarity and current flow alternates direction on a regular basis. Your home is an example of a system that is powered by AC.
Amp: A unit of electrical flow. In a water system, the flow of millions of water molecules would be expressed in terms of gallons per minute. In an electrical system, the flow of millions of electrons is expressed in terms of amps or amperes.
Apparent Power: The amount of power that is apparently consumed by a load. Apparent power is measure in VA or volt-amperes and is calculated by measuring the current consumed by the load and multiplying it by the voltage powering the load.
Common Mode Voltage: A voltage of any amplitude or frequency that is measured between the phase conductor and the ground conductor or the neutral conductor and the ground conductor. Neutral to ground voltage is a common mode component that frequently causes computer system malfunction. Neutral to ground voltages should always be limited to .5 volts (one half of one volt) or less.
Constant Voltage Transformer: Maintains a relatively constant output voltage for variations up to 20% in the input voltage. CVT’s are frequently a ferro-resonant style of transformer in which the voltage is regulated by means of current stored in a magnetic field. CVT’s are generally high impedance devices that are unsuitable for most modern computers with switch mode power supplies.
Current: The “flow” of electricity. Much like water, a current will follow the path of least resistance. As a result, electric current always finds the easiest path to ground. Current is measured in amps or amperes.
Dedicated Circuit: An obsolete method for providing clean, noise free power to a computer system. A dedicated circuit is one in which dedicated phase, neutral, and safety grounding conductors are run continuously from a distribution panel to an electronic load. The conductors may service only the dedicated load and the phase conductor must have its own circuit breaker. Furthermore, the dedicated conductors must run in their own dedicated metallic conduit or raceway with no other conductors present. The neutral and ground conductors may not be “daisy chained” or shared with any other circuit. The ability of dedicated circuits to guarantee a noise and disturbance free environment is insufficient for the high processing speeds, low operating voltages, and mission critical nature of modern technology.
Direct current (DC): An electrical system in which current flows in one direction only. A battery is an example of a direct current source.
Dip: See “Sag”.
Disturbance: Any departure from the nominal values of the power source. Disturbances can include transients, electrical noise, voltage changes, harmonics, outages, etc.
Drop: A slang word sometimes used to describe voltage sags or under voltages.
Flicker: A voltage variation of short duration but long enough to be noticeable to the human eye as a light flicker.
Frequency: In an AC system, the value of the voltage sinewave rises from zero to a maximum, falls to zero, increases to a maximum in the opposite direction, and falls back to zero again. This would describe one complete cycle. The number of complete cycles occurring in one second is called frequency. The General Conference on Weights and Measures has adopted the name hertz (abbreviated Hz) as the measurement of frequency. In North America, the frequency is 60 Hz. In Europe and most of Africa and Asia it is 50 Hz.
Glitch: A slang term for a voltage transient or voltage variation that causes equipment to misbehave..
Grounding Conductor: The physical conductor connecting the chassis of an electrical or electronic device to the electrical system’s grounding means. Sometimes referred to as the safety ground, this conductor may be a green insulated conductor, a bare copper wire, conduit, gutter or raceway. The purpose of the grounding conductor is provide a low impedance pathway for fault current in the event of a short circuit so that a circuit may be quickly de-energized to prevent a fire hazard or electrocution.
Grounded Conductor: Refers to the neutral conductor of the electrical system, which is bonded to the facility’s utility field earth reference in order to reference the facility electrical system to ground.
Harmonic: A whole multiple of the basic power frequency. On a 60 Hz system the 2nd harmonic is 120 Hz, the third harmonic is 180 Hz, the fourth is 240 Hz and so on.
Harmonic Distortion: The alteration of the normal voltage or current wave shape (sine wave) due to equipment generating frequencies other than the standard 60 cycles per second.
Impedance: Impedance is the opposition offered by a material to the flow of an electrical current in an AC electrical system. Impedance has two parts – resistance and reactance. Impedance is measured in ohms.
Interruption: See “Outage”.
Inverter: Device that converts direct current (DC) power into alternating current (AC) power.
Isolated Ground: An insulated equipment grounding conductor that is run in the same conduit as the supply conductors. This conductor is insulated from the metallic raceway and all ground points throughout its length. An isolated grounding conductor may only be connected to the grounding of the electrical system as a point where the facility neutral (grounded conductor) is bonded to ground. An example would be at the service entrance or at a distribution sub-transformer.
Isolation Transformer: A device that electrically separates and protects sensitive electronic equipment by buffering electrical noise and re-establishing the neutral-to-ground bond. By virtue of the neutral-to-ground bond, isolation transformers eliminate neutral-to-ground voltage – one type of common mode disturbance.
Line Conditioner: A device that provides for the electrical power quality needs of the connected electrical or electronic load. In the case of a linear power supply, a line conditioner might be a voltage regulator. In the case of a switch mode power supply, a line conditioner might be an isolation transformer with a noise filter and surge diverter. In the case of a simple electrical device like a motor, a line conditioner might be as rudimentary as a surge diverter. The term line conditioner is frequently misused. It must be understood that not all line conditioners function alike, and the capabilities of a line conditioner must be matched to the power quality needs of the connected load.
Linear Power Supply: A power supply which converts AC power into the DC power that is needed to operate an electronic circuit. In a linear supply, the AC voltage is first stepped down, then rectified, and then regulated using a series regulation device. Linear supplies obtain their name from the fact that there is a linear relationship between the value of the AC sine wave voltage and the power supply’s consumption of current from the AC circuit. Linear power supplies are generally less efficient because the series regulator dissipates large amounts of heat in the process of producing and regulating the DC output voltages. In addition, linear mode power supplies may require well regulated AC input voltage. One benefit of linear power supplies is that they produce little electrical noise.
Mission Critical Load: Devices and equipment identified as important or essential to the safety of personnel or the economic health of a business.
Momentary Outage: A brief interruption in power commonly lasting between 1/30 (2 cycles) of a second and 3 seconds.
Nines of Reliability: The reliability of an electrical system is a combination of both its availability (freedom from outages) as well as it’s quality (freedom from disturbances). Reliability is expressed in percentages. 99% would be expressed as two 9s of reliability. 99.9% would be three 9s reliable, 99.99% would be four 9s reliable and so forth. The average well managed electrical system in North America has about three 9s of reliability. In a 24 x 7 operation, that translates into about 88 hours per year in which the availability and quality of the electrical system are unsatisfactory to reliably power a mission critical electronic load.
Noise: An unwanted high-frequency electrical signal that alters the normal voltage pattern (sine wave). Noise may be either high amplitude or low amplitude.
Normal (Nominal) Voltage: The normal or contracted voltage assigned to a system for determining voltage class.
Normal Mode Voltage: Any voltage (other than fundamental 50 Hz or 60 Hz) that is measured between the phase conductor and the neutral conductor in a single phase system or between any two phase conductors of a three phase system. Normal mode voltage can be any amplitude or frequency. Normal mode noise voltages can interfere with the reliable operation of a computer system or degrade and destroy components. Normal mode power disturbances should be limited to 10 volts or less.
Ohm: A unit of resistance and impedance.
Ohms Law: The relationship between voltage, current and resistance in a DC circuit. If two values are known the other can be calculated. This relationship is expressed many different ways. The basic relationship is voltage (V) is equal to current (I) multiplied by resistance (R). Ohm’s law must be applied in a modified way to AC circuits. AC circuits have impedance rather than resistance. Impedance causes AC circuits to exhibit power factor, which must be factored into any calculations
Outage: Complete loss of electrical power.
Overvoltage: An increase in voltage outside the normal voltage levels (10% or greater) for more than one minute.
Phase Relationship: The timing relationship between voltage and current. If voltage and current cross through zero in a cycle at the same time they are said to be in phase. Phase differences are expressed in degrees. A cycle is 360 degrees. In a totally capacitive circuit, current leads voltage by 90 degrees. In a totally inductive voltage leads current by 90 degrees. In a circuit that is purely resistive, voltage and current are in phase.
Power Factor: The ratio between Watts and Volt-Amperes. This ratio is generally expressed as a decimal fraction. A power factor of 1.00 is unity.
Reactance: Reactance has two components, capacitive reactance and inductive reactance. The values of reactance are determined by the values of the individual capacitor or inductor as well as the frequency of the current flowing in the circuit.
Real Power: The amount of power that is actually consumed by the load. Real power is measure in watts and is calculated by measuring the current consumed by the load and multiplying it by the voltage powering the load and then multiplying by the power factor of the load.
Rectifier: A device that converts alternating current (AC) power to direct current (DC) power.
Reactive power: Reactive power is the difference between apparent power and real power. It is calculated by subtracting real power from apparent power. Reactive power is measured in VAR (volt-amps reactive) or kVAR (kilovolt/amps reactive)
Resistance: The opposition offered by a material to the flow of a steady electrical current in a DC circuit. Resistance is measured in ohms.
Sag: Any short-term (less than 1 minute) decrease in voltage.
Spike: See “Transient”.
Standby Generator: An alternate power supply usually driven by a gas or diesel engine.
Surge: A sudden dramatic increase in voltage that typically lasts less than 1/120 of a second.
Surge Protective Device (SPD): A device that is designed to limit instantaneous high voltages. Also known as a surge suppressor, surge arrestor and transient voltage surge suppressor (TVSS). These units are satisfactory for reducing the amplitude of catastrophic events. However, they function by diverting excess voltage to the safety ground of the electrical system. In the process they create a common mode disturbance which can disrupt the function of microprocessor based electronic systems.
Swell: Any short-term (less than one minute) increase in voltage.
Switch Mode Power Supply: A power supply technology in which the AC power is converted into DC power for use by an electronic system. SMPS technology uses switching transistors operating at very high speed to keep a capacitor reservoir sufficiently charged to produce the appropriate DC voltage needed by the electronic circuit. SMPS technology is very efficient because it does not utilize the “lossy” series regulator found in the linear power supply. Current is consumed from the circuit only when the charge state of the capacitor reservoir requires it. SMPS technology is “constant power” in that when line voltage decreases, the supply’s current consumption increases and when line voltage increases, current consumption decreases. SMPS technology is relatively immune to voltage regulation issues. However, the technology does not employ a stepdown transformer on the front end, which means that it does not satisfactorily isolate the electronic system from the electrical supply. SMPS technology produces electrical noise as a result of the high speed function of the switching transistors.
Transient: See “Surge”
True Power: See “Real Power”
TVSS: See “Surge Protective Device”
Undervoltage: A decrease in voltage outside the normal voltage levels (10% or greater) for more than one minute.
Uninterruptible Power Supply (UPS): A system designed to automatically provide power in the event that utility power is interrupted. A UPS may be standby, line interactive, or on line. A UPS is not necessarily a power conditioner, and care must be taken to ensure that the UPS provides all the power quality requirements that are needed.
Volt: A unit of electrical pressure. In a water system pressure might be expressed as pounds per square inch. In an electrical system, the pressure that causes electrons to move is called voltage. The voltage found in most homes is 120 and 240 volts. Businesses will typically utilize voltage at 120 and 208, or 277 and 480 volts.
Volt-Ampere (VA): The product of volts times amps. A kilovolt-ampere (kVA) is equal to one thousand volt-amperes. VA is also known as apparent power.
Voltage: The electrical “pressure” that creates the flow of current.
Voltage Regulator: A device that maintains output within a desired limit despite varying input voltage. These devices usually provide little to no protection against voltage transients or noise.
Watt (W): A unit of power equal to the product of the value of current of one ampere flowing in phase with the pressure of one volt. A kilowatt is a thousand watts. Watts are an expression of real or true power.
Watt-Hour (Wh): A unit of energy equal to the power of one watt for one hour. A kilo-watt hour is a thousand watt-hours.
Waveform Distortion: Any power quality variation in the wave shape of the voltage or current.
