WESCO | Voltage Sag compensation

FAQ

What does WESCO do?

WESCO is short for “Worldwide Energy Saving Corporation.” The company was founded in January 2001 and became the nation’s first company to develop solutions for instantaneous power compensation. This field was unknown and undiscovered in Korea back in 2001, and WESCO was the company that developed and supplied the element technology of the field. To prevent the “facility shutdown accident caused by voltage sag” in large-scale high-tech precision industry including semiconductor, display automobile, chemical, steel manufacture, tire, PCB, Solar power plant industry, and in SOC sector such as airports and ports, WESCO is supplying “Smart Power Vaccine^®” solution. TSP^® is the instantaneous power compensator that WESCO has developed with its own technical skills.

What is Smart Power Vaccine™?

Smart Power Vaccine^® helps preventing electrical virus such as instantaneous blackout and voltage sag by implanting electrical vaccine(Power Vaccine). With the vaccine, equipment or facilities can have tolerance to the accidents which is very important to maintain the normal operation when the accidents happen. It is nation’s only solution that provides Smart Information to prevent instantaneous electrical power accidents.

What is TSP^®?

TSP^® is the instantaneous power compensator that compensate, provide the normal voltage for about 1 second when the instantaneous blackout occurs. To maintain the normal operation of the equipment during the electrical accidents, super high-speed transfer switch turns on and provides the normal voltage with the power accumulated in Ultra-Capacitor which was built instead of a battery. In Korea the most voltage instability accidents in transmission or distribution network of KEPCO, 345kV or 154kV, is instantaneous voltage sag within 1 second. However, because of the blackout within 1 second, production lines and manufacturing equipment stop working. “Instantaneous power compensator” can provides electrical power reliably with super high-speed method of less than 2ms, to protect the facilities when 15% drop of voltage or even 100% blackout occurs. Sag-VIEWER™ enables users to verify various information including all sorts of accidents history, operation history through the built-in monitor of TSP^®products, and also, users can carry out remote meter reading with various communication methods such as Ethernet, USB, RS-485 and etc. By using Ultra-capacitor instead of a battery, it doesn’t need a cooling fan and users can save the maintenance and management cost.

What is Voltage Sag?

Voltage Sag and Voltage dip have the same meaning. Voltage Sag(Voltage drop) means the short drop of voltage caused by a fault in the system, short circuit, operation of the transformer or overload. It is the most common but most important electrical power quality problem. According to the IEEE standard(IEEE Std. 1159, 1995), Voltage Sag(Voltage drop) is defined as rms voltage decrease of from 0.1 to 0.9 per unit(pu) within the duration of 1 minute in 0.5 cycle.

What is Sag-VIEWER™?

Sag-VIEWER™ is TSP^®’s primary function that enables to operate “Smart Power Vaccine™.” It provides various information including the actual voltage sag history (Accidents voltage waveform, Compensation voltage waveform, Accident occurrence time, Accident Voltage, Accident duration, Accident history information and etc.), the operation history of TSP^®, the amount of power consumption and other useful information. Sag-VIEWER™ is the Application S/W that supports accident surveillance monitoring.

What is TSP^® Capacity?

Under 3-phase low-voltage standard such as AC 3-phase 208V, 220V, 380V, 440V, TSP^® can produce and provide the capacity of from 5kVA up to 2400kVA. – TSP^®Large Capacity

Under single-phase standard such as AC single-phase 110V, 208V, 220V, TSP^® can produce and provide the capacity of from 0.5kVA up to 20kVA. – TSP^®Small·Medium Capacity (compensation capacity supply other than the standard capacity is subject to customized order specification)

What is the power compensation time of TSP^®?

TSP^® standard follows the minimum 1-second instantaneous voltage sag or power compensation specification. (product with extended compensation time is special order product)

Does TSP^®’s 1-second compensation specification have proper grounds?

TSP^® standard compensation time, 1-second compensation function, is electrically capable. The facilities in the target sector, large high-tech precision new industry sector such as semiconductor, display, automobile, chemical, steel manufacture, tire, PCB, solar power plant industry and SOC sector get prime-power-entry voltage-specification of over 154kVA from KEPCO. The most common instability factor of facilities that use extra-high voltage of over 154kVA is the “instantaneous voltage sag less than 1-second.” Thus, as the countermeasure that compensates instantaneous voltage sag or blackout less than 1-second, facilities can replace the existing battery UPS which used to compensate the blackout of over 15 minutes, with “Smart Power Vaccine^®” which utilizes TSP^® that compensates 1-second without a battery. TSP^® is “no-battery instantaneous power compensator” which redeems the weak point of existing battery UPS, applied in a lump, due to the budget constraint. TSP^®aims to maximize the cost efficiency of the power compensation project. Which means that it aims to distinguish the target load of less than 1-second compensation time and the compensation target of over 30min. in average, to apply the different uninterruptable power supply devices according to the characteristics of the target loads. The unlimited power compensation method such as emergency generator system will be applied to the sectors that require over 15 minutes or unlimited power compensation (e.g. ER or OR in a hospital, SCADA in the semiconductor factory, computer room, exhaust system, fire service, safety service, emergency light and etc.).

How is TSP^® different from existing UPS?

TSP^®has special features as shown below that differentiate itself from the existing USP (Uninterruptible Power Supply) system.

Category	TSP^®	UPS	note
Energy accumulation medium	EDLC: Electrical Double Layer Capacitor, called “Ultra-Capacitor”	Storage battery mainly lead storage battery Recently with the change of the trend, lithium-ion battery is widely used.	Price may vary due to life time, maintenance and management, installation space and etc.
Energy Production Method	Physical reaction	Chemical reaction
Life time	15 years at room temperature	Generally about 5 years in average	Keeping constant temperature and humidity is necessary, as it tends to have shorter life time when the surrounding temperature is high.
Compensation time	Within 1 sec. ~ 5 sec.	Longer than 15 min. ~ 60 min.	Selectively applied in accordance with the target compensation time.
Installation of device for Constant temperature, Constant humidity	No additional device needed Least chance to have thermogenesis by using Off-Line method.	Necessary to install because thermogenesis always occurs with on-Line method.
Regular Maintenance (consumable supplies)	Not required	Necessary	Regular maintenance and periodic replacement of battery lifetime and cooling fan
Installation Space	100 is considered as standard	300	Battery installation place
Opinion	For less than 1 second instantaneous power compensation, TSP^®, for the blackout of over 5 minutes duration time, USP is reasonable to use.

Does the output waveform need to be sine waveform?

Yes, the compensation output is stable when the waveform is similar to the input Grid waveform. Generally, when compensating the square wave, due to the sharp increase in the current it can cause a bad influence by imposing a heavy burden on the load. Thus, to compensate the instantaneous voltage without burdening the load, it is effective to use sinewave for the compensation output.

How can I select the precise TSP^® standard that matches the use of application?

There are three ways to select the corresponding standard, explained in the additional reference. Considering the operational safety net and further load components extension, we recommend you select the TSP^® which has 20-30% larger capacity than the calculated capacity. Occasionally, actual load capacity can be used depending on the load characteristics.

What should I do when I need longer than 1 minute of compensation time?

Two options are available. The first option is to use the next size of the 1-second standard type model. For example, 3kVA TSP^®has the compensation time of 1 second under 3kVA load. On the other hand, TSP^®3kVA has the compensation time of 3 seconds under 1kVA load. Time and load have an inverse relationship. The second option is to use storage capacitor. This is a customized order which can be supplied upon the special order of client.

What should I do if the load power factor is higher than the regular power factor in the MCC and switchboards?

Generally, these loads consist of contactors, relays, and starters, thus the power factor as an inductive load is relatively low, about from 0.15 to 0.3. If the control circuit consists of PLC, power supplier and other real power load, it has to be considered in the selection of TSP^® size. In other words, there are two ways to select. You can select one size larger TSP^®, or you can use the storage capacitor that should be specially ordered. (in the case of 3-phase)

What should I do if I need TSP^® with larger capacity?

It can be supplied upon special request of client. It needs more capacitor of larger scale, and the semiconductor and static switch have to be upgraded.

Do I use multiple number of TSP^®s with small capacity? or Is it better to use oneTSP^® with large capacity?

It depends on the structure of control circuit. When many control transformers connected to one starter or contactor, proper number of TSP^®s with smaller capacity are needed. On the other hand, one control transformer with large capacity supplies various control items under common control bus, one TSP^® with larger capacity has to be used. Also, installation site and management viewpoint for maintenance need to be considered too.

Isn’t it inefficient if I use many TSP^®s with small capacity?

If possible, control circuit needs to be consolidated and the partial reconnection cost for this work needs to be considered. In this way, medium size or large size TSP^® can be installed. However, it can be difficult to consolidate and use one TSP^® because different timer settings are needed for many different loads. The best option is to use several medium-size units which can adjust its setting according to the cognate loads.

What is the optimal way to set the timer?

It can vary depending on the two factors as stated below:

1) Timer is set to cope with the worst-case scenario measured in the power quality monitoring research, conducted by the client company or the power supplier.

2) Loads with high inertia, such as conveyor, ventilator and fan can operate for many seconds without the noticeable decline in speed and can be connected for a long time. Loads with low inertia, such as pump, chiller and compressor can sharply decrease its speed in a very short time(300-500 milliseconds) and the speed continues to decrease until it reaches the point where the connection cannot be maintained and the syntonic operation of the total system is impossible at this point. Most application specifications are different from each other. We can support any special requests of yours.

Note) It is very dangerous to reconnect and operate the motor by the motor starter or contactor which declined after the voltage sag.

If the power is reapplied after the power problem, when the motor speed sharply drops and deviates from the syntonic speed, double voltage would pass the motor terminal which can cause excessive torque in the motor shaft and it also can impose electrical/mechanical stress on the system.

However, if the motor connection is maintained during the total interruption, the power current is allowed to pass the secondary circuit or other parallel loads. Thus, the system stress is reduced because the load voltage in motor terminal drops until it reaches more allowable level (e.g. Rapix Flux Decay). Also, when the system keeps maintaining the connection, a little voltage remains in the circuit, which means the power supply won’t be aperiodic. Under the voltage decrease condition, it is not a big problem.

How much heat does TSP^® release?

Although there are formed housing and fins for cooling, TSP^® releases almost no heat because it is operated by off-line.

TSP^®’s compensation circuit will not operate until the instantaneous voltage sag actually occurs. Only the static switch releases a bit of heat because it is located in parallel with the load and it always stays in the circuit. TSP^® takes no-cooling method which doesn’t need an additional cooling fan, and compare to the UPS system, it has an advantage as it has no maintenance factor.

How much power does it take to operate TSP^® and charge Ultra-Capacitor?

Under the general operation condition, all unit consumes about 10 watts. Under 120V, this is equal to +/- 200 mA.

Without the battery, what kind of capacitor is used as the energy storage medium, and how long is its life time?

EDLC, Electrical Double Layer Capacitor/Ultra-Capacitor, with low voltage, long life time is used. We select the models produced by excellent manufacturers based on the life time, ripple current capability and reliability.

All models are operated under the ideal condition with the rated operating temperature of from - 40°C to + 65°C and they can be charged with low operating voltage. They have no ripple current. It has long life time of about 10 years, under the outdoor temperature average of 25°C.

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