Modern industry is becoming more automated and the sensitivity of processes to power quality events is increasing.

It is generally recognized that quality is an important aspect of the electricity service. Not only low prices are important, also high-quality matters to customers. Price and quality are often complementary aspects; together they define the value that customers derive from consuming electricity.

In practice the voltage is never perfect.

If the quality of electricity supplied to the plants drops below a certain level, equipment no longer works properly and customers are likely to experience problems. Sensitive industry sectors may incur a Power Quality cost up to 4% of their turnover, with about 60% of those costs caused by voltage sags and short interruptions.

The cost of a voltage sag is usually lower than the cost of an interruption, either short or long, but sags are much more frequent. An interruption will affect all (unprotected) services, sags may affect only those

that are most sensitive.

Many businesses require voltage or power conditioning rather than battery back up power, provided by UPS system. In those cases where back-up power is unnecessary, a voltage conditioner provides superior protection and additional power quality functions, such as protecting against over/under voltage, voltage fluctuations, sags and dips.

Moreover protecting a whole plant by UPS, which can guarantee sags immunity, may be very costly, due to battery and maintenance costs.

The right solution is the sag compensator.

What are voltage sags?

A voltage sag is a short-term reduction in, or complete loss of, nominal voltage. Generally voltage sag happens when the nominal voltage decreases between 10 and 90 percent of nominal voltage for one-half cycle to one minute. There are two main causes of voltage sags; starting of large loads either on the affected site or by a consumer on the same circuit and faults on other branches of the network.

Motor drives, including variable speed drives, are particularly susceptible.

Data processing and control equipment is also very sensitive to voltage sags and can suffer from data loss and extended downtime.

Relevance of voltage sags

The more modern the equipment is and the more electronics is required, the more serious are the problems caused through voltage sag. With the increasing number of regenerative energy sources, energy sags, fluctuations and frequency deviations also increase.

Example of costs due to voltage sags:

Costs for unproductive personnel due to the sudden termination of the production cycle.

Costs for raw materials and production lost.

Costs for damages and/or malfunctions of machineries (repairs to them, temporary hire of new ones).

Penalties caused by contractual shortcomings.

Sanctions for damage to the environment.

Increase in general insurance costs.

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SAG COMPENSATOR

Oxygen

Ortea
Manufactured by: Ortea
Model: Oxygen
Product ID: 5661
three-phase
200 - 3200kVA

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Input voltage compensation
Oxygen 10-40: ±10% cont. / -40% for 1 min. (100% Vout)
Oxygen 15-50: ±15% cont. / -50% for 1 min. (100% Vout)
Standard features
Voltage regulation IGBT control (double conversion technology)
Voltage stabilisation Independent phase control
Available nominal voltage* 380-400-415V (440-460-480V**)
Output voltage accuracy ±0,5%
Frequency 50Hz ±5% or 60Hz ±5%
Correction time <3 millisecs
Admitted load variation Up to 100%
Admitted load imbalance 50%
Cooling Forced ventilation
Operating temperature range 0/+40°C
Max relative humidity <95% (non condensing)
Admitted overload 150% for 1 minute (at nominal imput voltage)
Colour RAL 9005
Protection degree IP21
User interface 10" color touch panel, multilingual (on request remotely available by dedicated software connected to the same network - Ethernet)
Installation Indoor
Communication system MODBUS RTU (RS485)
Overvoltage protection Input class I surge arrestors Output class II surge arrestors
Protection Automatic by-pass protection
* The output voltage can be adjusted by choosing one of the indicated values. Such choice sets the new nominal value as a reference for all the stabilizer parameters. ** 60Hz only.
Accessories
  • Input automatic circuit breaker
  • Short circuit output protection
  • Manual maintenance by-pass
  • Input isolating transformer
  • EMI/RFI filters
  • IP54 protection degree for indoor and outdoor installation
Oxygen, thanks to a suitable sizing of the power components and a remarkable response speed ( The energy required is taken directly from the network. The voltage compensation on the buck/boost primary winding is performed by IGBT static switches controlled by a microcontroller. The microcontroller system monitors the output voltage and determines the opening or closing of the IGBT contacts ensuring the best regulation. The use of the double conversion technology guarantees the insulation from the disturbances and the distortions of the network and, together with the help provided by the electrolytic capacitors, makes it possible to build machines for high power loads. This Sag compensator can operate with a load variation range for each phase from 0 to 100%, it is not affected by the power factor of the load and they can work with or without the neutral wire. Oxygen can operate with different input and, consequently, output voltage (380V or 415V) from the nominal one (400V). The main components are:
  • IGBT microcontroller-based electronic control boards running the system in terms of regulation and alarm management. They compare the output voltage value to the set one: if a difference is detected, they generate the compensation necessary to bring back the output voltage to the nominal value (provided that said difference falls in the working range).
  • Conversion units (AC/DC rectifier and DC/AC inverter):Rectifier: it converts the phase to neutral voltage of the AC mains into DC voltage by means of a fully-controlled IGBT bridge. The rectifier is sized in order to supply the inverter at full load.Inverter: it converts the DC voltage coming from the rectifier into AC voltage, stabilised in amplitude. The inverter uses the same IGBT technology as the rectifier.
  • Internal by-pass static switch enabling load supply in case of fault condition.
  • Buck/boost transformer adding or substracting the voltage necessary to compensate for the mains fluctuation.
  • Touch display.
The user interface is created using a multilingual «touch panel» (10"); through the selection menu, it is possible to display electrical values and set the operating parameters of the stabilizer. It is also possible to communicate with the electronic component via the RS485 serial bus using the Modbus RTU protocol. The standard cabinet is metallic with RAL9005 color and IP21 protection degree.
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