FAQs

The principle of operation of Servo Stabilisers comprises comparing the output voltage through the sensing circuit, a reference voltage source. The control circuit operates the motor whenever the output voltage falls or rises beyond a preset voltage. The secondary winding of the buck-boost transformer is in series with the main supply. The primary winding is connected to the motorised control autotransformer (Variac). Output voltage variation due to any reason makes the motor move in the proper direction to feed the primary of the buck-boost transformer a proper voltage which in turn produces a voltage in the secondary to keep the output to a set level with a tolerance of ±1%.

Static Voltage Stabilisers do not use any moving parts like Servo Motor; instead, they use semiconductor devices like thyristor / IGBT for changing the transformer taps to regulate the voltage. The speed of correction is higher in such types of stabilisers.

These types of stabilisers use relays for changing the transformer taps with an input sensing method to regulate the voltage. They have less accuracy and are basically used for domestic loads / non-critical loads.

A constant voltage transformer (CVT) or ferroresonant transformer (Ferro) is a non-linear transformer that provides a regulated voltage output passively through the electromagnetic phenomenon of ferroresonance (where the term ferroresonant transformer was derived). Ferroresonance describes the behaviour of iron cores near a point of magnetic saturation, where the core is so strongly magnetised that any further variation in the input voltage results in little or no increase in magnetic flux. The ferroresonant action, rather than being a voltage regulator, is a flux limiter. Despite this, the CVT can maintain an almost constant output voltage even when the input voltage varies greatly with a relatively constant supply frequency.

A power conditioner is a device that improves the quality of power delivered to equipment. Generally, it is a voltage regulator that protects against electrical noises, transients, etc.

An isolation transformer is a transformer, often with symmetrical windings, which is used to decouple two circuits. An isolation transformer allows an AC signal or power to be taken from one device and fed into another without electrically connecting the two circuits. Isolation transformers block the transmission of DC signals from one circuit to the other but allow AC signals to pass. They also block interference caused by ground loops. Isolation transformers with electrostatic shields are used for power supplies for sensitive equipment such as computers, Lab Instruments, CNC Machines, Medical equipment, etc.

The K-factor is a weighted average of harmonic load currents based on their effects on transformer heating. A linear load is indicated by a K-factor of 1.0. (no harmonics). The greater the harmonic heating effects, the greater the K-factor.

Transformer manufacturers and their customers use the K-Factor to adjust the load rating based on the harmonic currents caused by the load (s). Transformers are offered with different K-Factors (K-4, K-7, K-13 & K-20) standards. The K-Factor is a means of rating the transformer's ability to withstand the heating effects of harmonic and fundamental current flowing in the transformer. Utilization of the proper K-Factor is essential in every installation. If a K-Factor is too low, it can result in failure, fire, overheating, and waveform distortion.

A power surge occurs when the voltage exceeds 110% of normal. The most common cause is the failure to turn off heavy electrical equipment. Computer systems and other high-tech equipment may experience flickering lights, equipment shutoff, errors, or memory loss under these conditions.

High-voltage spikes occur when there is a sudden voltage peak of up to 6,000 volts. These spikes are usually the result of nearby lightning strikes, but there can be other causes as well. The effects on vulnerable electronic systems can include loss of data and burned circuit boards.

Electrical transients are brief bursts of energy caused by power, data, or communication lines. They are distinguished by extremely high voltages that drive enormous currents into an electrical circuit for a few millionths to a few thousandths of a second. Large transients on the power system originating outside a facility are best diverted at the facility's service entrance. Transients generated within the premises must be diverted by SPDs located close to the internal source of the transients or, if this is not possible, close to the electronic load equipment. The optimal results are obtained when both locations are safeguarded.

A frequency variation involves a change in frequency from the normally stable utility frequency of 50 or 60 Hz, depending on your geographic location. The erratic operation of emergency generators or unstable frequency power sources may cause this. For sensitive equipment, the results can be data loss, program failure, equipment lock-up or complete shutdown.

Electrical line noise is defined as Radio Frequency Interference (RFI) and Electromagnetic Interference (EMI) that causes unwanted effects in the circuits of computer systems. Sources of the problems include motors, relays, motor control devices, broadcast transmissions, microwave radiation, and distant electrical storms. RFI, EMI and other frequency problems can cause equipment to lock up and data error or loss.

A brownout is a steady lower voltage state. An example of a brownout is what happens during peak electrical demand in the summer when utilities can’t always meet the requirements. It must lower the voltage to limit maximum power. When this happens, systems can experience glitches, data loss and equipment failure.

A power outage, also known as a blackout, is a zero-voltage condition that lasts more than two cycles. It could be caused by a tripped circuit breaker, a power distribution failure, or a utility power outage. A power outage can cause data loss or corruption, as well as equipment damage.

Sag is a reduction of AC Voltage at a given frequency for the duration of 0.5 cycles to 1 minute. Sags are usually caused by system faults and often result from switching loads with heavy start-up currents. Common causes for sags include starting large loads like large Air Conditioning units, starting heavy motors, etc. Sags coming from the utility have a variety of reasons, including lightning, animal and human activity, and normal and abnormal utility equipment operation. Sags generated on the transmission or distribution system can travel hundreds of miles, thereby affecting thousands of customers during a single event.

Undervoltages are caused by long-term problems that cause sags. The term 'brownout' was commonly used to describe this problem, but it has now been replaced by the term 'Undervoltage'. Undervoltage causes motors to overheat and can cause equipment failure.

Harmonics are currents or voltages with frequencies that are integer multiples of the fundamental power frequency, which is typically 50 or 60 Hz (50Hz for European power and 60Hz for American power). For example, if the fundamental power frequency is 50 hertz, the second harmonic is 100 hertz, the third is 150 hertz, and so on. Harmonics are produced and caused by such "non-linear" loads and any other equipment powered by a switched-mode power supply (SMPS).

For years, electricity was predominantly used to power motors, lights and heating devices. These early technologies are “linear loads”, meaning that the current rises and falls in proportion to the voltage wave. As such, they have little effect on the 50-Hertz base sine waveform.

In recent years many new technologies that distort the waveform have emerged. Because their current flow is not directly proportional to the voltage, these new technologies are called “non-linear” loads.

“Non-linear” loads include Variable Speed Drives, UPS, PLCs, Computers, Printers, Solid State Rectifiers, Induction Heating Equipment, Sodium and Mercury Vapour Lighting, Arc Furnaces, Welding equipment, AC/DC Converters, Electronic Ballasts, etc.

Harmonic Distortion often causes the following symptoms:

• Malfunctioning of microprocessor-based equipment
• Overheating in neutral conductors, transformers or induction motors
• Deterioration or failure of power factor correction capacitors
• Erratic operation of breakers & relays
• Pronounced magnetic fields near transformers & switchgear

In regular operation, the Online UPS supplies power to the AC load via the Rectifier and Inverter Combo and uses an inverter to supply power during a power outage. As a result, the output power supply is always on, and switching is unnecessary. As a result, there is no time delay when switching between its sources. Even if power fails for a nanosecond, there is no interruption.

Offline UPS, or standby UPS or battery backup, is a low-cost option. In normal operation, the offline UPS directly supplies power to the AC load from the AC mains and uses an inverter to power the AC load from the DC battery. Because there are two separate supply lines, it is necessary that the output supply must be switched between the two.

The offline UPS's switching speed is around 6 - 8ms, which is enough to keep a computer from shutting down but not fast enough to keep sensitive equipment running smoothly.

The offline UPS's switching speed is around 6 - 8ms, which is enough to keep a computer from shutting down but not fast enough to keep sensitive equipment running smoothly.

Line-interactive UPS systems provide power conditioning and battery backup. This technology is especially useful in areas where outages are uncommon, but power fluctuations are common. Before switching to battery backup, line-interactive UPS systems can tolerate a wide range of input voltage fluctuations. The switching speed of an offline UPS is around 4 - 6ms, enough to prevent a computer from shutting down but not fast enough to keep sensitive equipment running smoothly. Line-interactive UPS and battery backup provide far better control over power fluctuations than offline systems.