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"Potential-REX" device
Control of quality characteristics of electric energy.
Development of hi-tech productions and introduction of the new technologies consuming the big capacities of electric energy, besides doubtless advantage for a society has brought also the problems connected with quality deterioration of electric energy delivered to consumers.
Meanwhile, the poor quality electric power leads not only to damage of electrical networks and the consumer equipment, but also can harm health of the person. Quality control of electric energy means conformity assessment of indicators to the established norms.
Currently at the existing tendency of production development increasingly emerge a question about certain quality characteristics to which it should correspond. At the enterprises the newest equipment is established, specialists go on retraining, ISO 9000 certification is carried out … However few people think that electric energy – without which any production is impossible – also should corresponds to quality characteristics.
Definition of indicators of quality of electric energy is a difficult task.
Because the majority of the processes proceeding in electrical networks are swift-flowing, therefore indicators of quality of electric energy can't be measured directly — firstly they need to be counted, and the final conclusion is possible to provide only on base of statistically processed results. Therefore, for definition of indicators of quality of electric energy, it is necessary to execute great volume of measurements with high speed and simultaneous mathematical and statistical processing of the measured values. For this purpose is used different devices which basic difference is that they can measure only one or several parameters.

Until quite recently there was no possibility to estimate quality of the electric power - as wasn't professional and properly certificated equipment that didn't allow the parties of energy supply agreement to collect damage from the causer of entering of distortion in an electric network.

BASIC MATERIALS
The situation has now changed for the better: appropriate devices enabling control over quality parameters of power, quality expertise, and mandatory certification of electric power have been finally developed. One of such devices was developed by our company.
Multi-parametric multifunctional device “Potential-REX” for quality control of electrical energy at input power utilities allows the setting of specific requirements under specific customer’s equipment. That’s the main difference from a bunch of other analogues.
Main purpose of the device is to ensure the oscillography for form of voltage and current in emergency situations (short circuit, disconnection of power supply, switching noise, and other emergency modes) and record the quality parameters of power in electric networks of three-phase or one-phase alternating current (50 Hz frequency) – with option of their subsequent viewing at PC.
Recorder is designed for embedding into switchgear, substations.
The device is focused on functional use within SES automatic control systems of energy-consuming facilities (including geographically separated ones) as device for collection, primary processing, and accumulation of data on parameters of power supply (power consumption) and state of power-consuming facilities (electric equipment).
In the course of work, memory of the recorder collects electrical parameters of network – both in case of emergency and at normal operation. Record of parameters measured and calculated by recorder is ensured by two channels: channel recording the emergency situations and channel recording the normal operation parameters. All events fixed by recorder are time-bound to system clock.
Channel recording the emergency situations is designed for record of network parameters in case of accident. Each recorded emergency situation corresponds to one file in the memory. File size is determined by duration of emergency. Number of files is only limited by size of the memory. Use of PC enables the viewing of recorded information – in the form of voltage and current oscillograms.
Options of recorder allow 0 to 500 ms setting of record time for emergency background. Recording time of the emergency as such may be chosen either equal to its duration or equal to any time interval in the range of 0 to 60 minutes. Number of stored oscillograms (emergency situations) varies from 1 to 10000 – depending on their duration.

Recorder calculates the following values:
- phase voltage root-mean-square (rms) values;
- line voltage root-mean-square values;
- phase current root-mean-square values;
- zero sequence voltage;
- zero sequence current;
- total for three phases real power, reactive power, total power;
- individually for each phase real power, reactive power, total power;
- total power factor (min or max);
- power factor individually for each phase;
- zero sequence power factor;
- phase angle between zero sequence voltage and current.

The recorder functionally consists of the calculator module, analogue input module, control module, optionally – discrete input/ output module for arranging the relay protection.

The calculator module performs the following functions:
- measuring the current and voltage parameters;
- recording the voltage and current waveform oscillograms in device memory in the event of emergency situations;
- recording the quality parameters ЭЭ (according to GOST 13109-97);
- data exchange with the analogue input module, control module and discrete input/ output module;
- data exchange with the external devices via RS-485 bus and Ethernet;
- transfer of collected data via USB-interface using standard flash-disk.
Analogue signal input module.
Measuring circuits of the recorder consist of four inputs for measuring the voltage and seven inputs for measuring the current; four of these inputs are designed for measuring the current in the normal operation mode, and the other three ones – for measuring the high currents. In case of using the measuring transformer these three inputs serve for its connecting to relay winding.
The recorder measures voltage and current at direct connection to mains and connection via the standard measuring transformers. In the later case, the circuits for measurement the current in normal mode are connected to measuring winding of the current transformer, and the circuits for measurement of high currents – to relay winding. The maximum values of the measured current and voltage depend on the used measuring transformers.

If direct connected to the network recorder allows to measure and record:

- AC voltage in the range from 0 to 500 V (RMS);
- DC voltage in the range from 0 to 700;
- Nominal alternating current from 0 to 11 A (rms value);
- High-amperage alternating current from 0 to 140 A (rms value);
- Rated direct current from 0 to 15 A;
- High-amperage alternating current from 0 to 200 A.

Box’ measuring circuits are not galvanic coupled to each other and with a global bus. Recorder input circuits connecting is possible according to the ''triangle'' and ''Star'' scheme.
Display and control module consists of a two-line alphanumeric indicator and keyboard so that you can view the current parameters and input settings.
Discrete input/output unit is optional and is used for the relay protection.

Fig. relay protection logical scheme

In engineering way, registrar is monolithic boxes inside of which electronic boards are mounted that perform the functions of units described above.
The main technical characteristics of the instrument

Certificate

Another important point is a measuring instrument type approval certificate of certificate and its number in the State Register of Ukraine and Russia. That’s hardly to be wondered at the fact that type certificate have to be issued for each measure. Only this certificate entitles the use of this type of measures in Ukraine and in the Russian Federation.


Lightning protection

 

Lightning protection is a set of organization measures and special technical devices that protect buildings, equipment and people from damage caused by direct lightning strikes and/or pulsed electromagnetic field, disabling sensitive equipment. In the world science and practice effective lightning protection methods have been created. Currently lightning protection, as a set of rules, methods and tools, is apart of world most dynamically evolving machines.

The complex of modern inside and outside lightning protection provides:
• protection of people
• Object protection from thermal and mechanical damage
• Protection of electrical low-voltage network (0.4 kV), sensitive equipment of telecommunications, electronic and engineering systems from the secondary effects (electromagnetic influence)
• High level of electrical protection
• electromagnetic environment improvement

To protect your equipment from surge overvoltage caused by lightning electromagnetic field surge protection device is used.

There are four basic types of devices for surge overvoltage protection:

Discharger
A discharger is a device composed of two conducting plates with a calibrated gap. When voltage rises significantly, a circular charge occurs between the plates that resets the pulse to ground. There exist several models of discharges: air, air multi-electrode and gas dischargers. The arch chamber of gas discharger is filled with inert low-pressure gas. Due to this their parameters depend little upon the ambient conditions (humidity, temperature, dustiness etc.). Besides, the resistance of gas dischargers is extremely high (about 10 GOm) that allows to apply them for protection of high-frequency devices with frequency of up to several GHz. When installing the air dischargers one shall take into consideration that hot ionized gas is emitted from the arc chamber, that is extremely important when installing the dischargers into plastic plate structures. The typical actuation voltage of dischargers is 1.5 – 4 kV (for the network with frequency of 220/380 V, 50 Hz). The actuation time is about 100 ns. The maximum current rate at discharge in various models is 45 to 60 kA at the pulse length of 10/350 µs. The devices are designed either as separate elements to be installed in the plates or as modules to be installed on DIN-racks. A separate group is represented by the dischargers designed as elements to be installed on plates with discharge current rate of 1 to 20 kА (8/20 µs).

Variable Resistor
A variable resistor is a ceramic element, the resistance of which drops suddenly when a definite voltage limit is exceeded. The actuation voltage is 470 – 560 V (for the network with frequency of 220/380 V, 50 Hz).
Actuation time does not exceed 25 ns.
Maximum pulse current rate is 2 to 40 kА at the pulse length of 8/20 µs.
The devices are designed either as separate elements to be installed in radio equipment or as DIN-modules to be installed in power shields.

Isolation transformer
A separate-winding power transformer with frequency of 50 Hz with equal input and output voltage. The transformer simply cannot transfer such a short high-voltage pulse to the secondary winding, so it is to some extent the ideal protection from pulse surging. Nevertheless, if the lightning strikes the electrical network directly, the integrity of primary winding isolation may be disrupted and the transformer may break down.

Protective Diode
As a rule, it applies to protect communication equipment. It has high responding speed (less than 1 nanosecond) and a discharge current of 1 kiloampere at a current pulse of 8/20 microseconds.
From the four devises, mentioned above, each has its advantages and disadvantages. If we compare the guard and the varistor with the same maximum pulse current and pay attention to the duration of the test pulse, it becomes clear that the guard can absorb the energy twice as much as the varistor. But the varistor responds faster, the response voltage is much lower and it has much less interfering signals when operating.
The insulating transformer, under certain conditions, has an unlimited resource to protect the load from a pulse surge (degradation failure of the element`s material takes place at the moment of response in varistors and guards), but for the 100 kVA network a 100kVA transformer is required (heavy, overall and quite expensive).
It should be kept in mind that if you disable the primary network, a transformer itself generates a high voltage release that requires installation of varistors at the transformer output.
Our lightning guard unit is designed for protection against surge voltage in communication circuits as a result of lightning discharge.
Lightning guard unit is a case comprising integrated printed-component board. Oxide-zinc voltage-sensitive resistors and gas-discharge guards are the main protective parts. In case of overvoltage in communication circuits voltage-sensitive resistor limits voltage and in case of further voltage increase input discharge guard is activated and temporarily closes communication circuit with ground, thus preventing from pulse penetration to device being protected. Lightning guard unit is installed between communication line and equipment.
Lightning guard unit should be connected to grounding bus.
Our lightning guard unit has specifications comparable with more expensive models and the best ration price-quality for analogues. But is has vast opportunities for further improvement and modification. Therefore, the following development strategy has been developed:
• Not chase the number of models. It’s better to finish off thoroughly and make the available construction as cheap as possible.
• Create modification for various conditions of operations on the basis of existing unit.
• Keep the price as low as possible to make it available for the most of applicants.
• Develop manuals and user’s operation guides for our devices, and share information and experience.
One more thing we would like to highlight ... Sometimes we are told about the pointless rivalry with foreign producers (manufacturers of thunderstorm and lightning guards). We can say the following.
First, they have the same employees as we do.
Secondly, go off the beaten track and create more complex models is much easier than working from the start.
Thirdly, higher price of western analogues is caused by higher advertising spending and the fact that western companies have a well- paid stuff, higher research funds, software products spending and intermediaries’ profit. A lightning protection device as it's not a TV therefore they less people buy it. Therefore, producers have to raise prices on their products more often explaining their high price with “magic” characteristics which are often highly overrated. Indirectly, these words prove the fact that the number of large and well-known producers is gradually reducing. As a result the market is represented by either giants with substantial orders, or by very small companies and firms with a small but sufficient profit :-)