It is simply impossible to imagine the life of a modern person without electricity and various electrical appliances. The assembly of various units and electrical circuits can be done independently. It is only necessary to exactly follow the existing documentation, as well as to measure the impedance phase-zero circuit, which will ensure the trouble-free operation of electrical equipment and its complete security.
Content
- Protection parameters
- What is the measurement for?
- Existing calculation methods
- Used high-precision instruments
Protection parameters
Electric current is destructive, therefore it is dangerous for equipment, material values and living organisms. In the past, to protect against high voltage damage, various insulations from dielectrics were used and measurements of the parameters of the operation of power lines were carried out.
Today, when operating a variety of electrical devices, all kinds of protective devices are used shutdowns and circuit breakers that ensure complete operational safety equipment. Protective measures are also applied, including separation of the working zero and grounding of electrical engineering.
During operation, the parameters of the power grids and the equipment used may change, which is explained by the peculiarities of the operation of the equipment and the wear of the power lines.
It will be necessary to check on a regular basis that the current characteristics comply with the required standards for the safety of electrical networks. This is the only way to ensure complete trouble-free operation of equipment, while simultaneously excluding electric shock.
The following measurements and control are carried out:
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Checking DIF machines and RCDs. - Testing the load current of circuit breakers.
- Measuring the resistance of the circuit.
- Phase circuit measurement.
- Measurement of insulation resistance.
- Testing of other protective process equipment.
Such work is not particularly difficult, therefore, having initial skills in electrical engineering and using the appropriate equipment, everything is possible take measurements on your own, which ensures the correct operation of the equipment and saves the homeowner's expenses on contacting professional specialists.
The control of the parameters of the power grid is carried out on an ongoing basis, regardless of the type of devices and their modes of operation.
What is the measurement for?
The main task of measuring the phase-zero loop is to protect cables and electrical equipment from overloads that may occur during the operation of equipment. The high resistance of the electric cables leads to overheating of the line, which, ultimately, can provoke a short circuit and a fire. The phase indicators are influenced by various parameters, including the environment, the characteristics of the overhead line, the quality of the cable.
When making measurements, it is mandatory to include the contacts of the existing automatic protection, contactors, circuit breakers, voltage conductors to electrical installations. As such conductors, power cables are used, which are fed to the phase-zero to the powered equipment.
Phase-zero impedance is calculated using special formulas that take into account the material and cross-section of the conductors, the length of the line and a number of other parameters. You can get the most accurate measurement results only by examining the physical circuit to which various electrical devices are connected.
If there is a residual current device in the electrical circuit, it must be disconnected during measurements, which allows obtaining the most accurate data. The RCDs used when passing large currents de-energize the network, so it will be impossible to obtain reliable results.
Existing calculation methods
Zero-phase measurement can be performed using various techniques. In industry and with electrical equipment, where the highest possible accuracy of calculations is required, special devices are used that have a minimum error. Also, in this case, appropriate formulas are used that take into account various factors affecting the quality of the data obtained. In a domestic environment, it will be enough to use the simplest meters, which will help to obtain the necessary information.
The most widespread are the following methods for measuring the phase-zero loop:
- Voltage drop method.
- Short circuit method.
- Using an ammeter-voltmeter.
When using the voltage reduction method all measurements are carried out when the load is disconnected, after which a load resistance with a pre-calculated value is included in the circuit. Using a special device, the value of the load in the circuit is measured, after which the resulting the results are checked against the standard, the corresponding calculations are carried out, which are compared with regulatory data.
Short circuit method in a circuit means connecting a special device to the network that creates artificial short circuits at the point required by the consumer. With the use of special devices, the magnitude of the short-circuit current is determined, as well as the response time of the protection. The data obtained is checked against the standard indicators, after which the compliance of the electrical circuit with the current standards and requirements is calculated.
When using the ammeter-voltmeter method remove the supply voltage from the circuit, then connect a step-down transformer to the network, close the phase wire of the existing electrical installation. The obtained data is processed, and, using special formulas, the necessary parameters are determined.
The most widespread today is received method for measuring the phase-zero loop by connecting the load resistance. This method combines ease of use, maximum accuracy, so it is used both in everyday life and when it is necessary to obtain ultra-precise data. If it is necessary to monitor the phase indicator in one building, the load resistance is connected in the farthest accessible section of the circuit. The devices are connected to pre-protected contacts, which will avoid voltage drops and weakening of the current.
Initial measurements are performed without connecting the load, after which a control with an accurate load is carried out using an ammeter. Based on the results of the data obtained, the resistance of the phase-zero loop is calculated.
It is also possible to use special devices, which using the appropriate scale allow you to obtain the required resistance, ensuring the highest possible accuracy of the calculated data.
When measuring this indicator, the calculated data is enough to determine the quality of the electrical network in everyday life. In the industry, when performing the appropriate control, a protocol is drawn up, where all the obtained values are entered. In such a protocol, the corresponding calculations are performed, after which the paper is signed by engineers and attached to the general regulatory and technical documentation.
Used high-precision instruments
For phase measurements and calculations, both standard ammeters and voltmeters, the use of which is not difficult, and highly specialized devices can be used. The latter ensure the highest possible accuracy of the obtained data on the parameters of the power grid. The most widespread are the following measuring devices.
M417 Is a reliable device proven over the years, designed specifically for measuring the resistance indicator in the phase-zero circuit. One of the features of this device is the ability to carry out all work without removing the power supply, which greatly simplifies monitoring the state of the electrical network. This apparatus uses the voltage drop method to ensure the highest possible accuracy of the calculations obtained. It is allowed to use M417 in a circuit with a dead-grounded neutral and a voltage of 380 volts. The only drawback of using this tool is the need to calibrate the device before starting work.
MZC-300 - a measuring device of a new generation, which is built on the basis of a powerful microprocessor. The instruments use a voltage drop method with a 10 ohm resistor connected. The MZC-300 provides a measuring time of 0.03 seconds and can be used in networks with a voltage of 180-250 Volts. To ensure the accuracy of the data, the device is connected at the far point of the network, after which the Start button is pressed, and the result obtained is displayed on a small digital display. All calculations are performed by a microprocessor, which greatly simplifies phase control.
IFN-200 - a multifunctional device that allows you to perform phase measurements. The device operates with a voltage of 180-250 Volts. Suitable connectors are provided to simplify network connection, and the use of this device is not difficult. The limitation on the measurement in the circuit is 1 kOhm, when exceeded, the protection is triggered and the device is turned off, preventing its overload. The device is based on a powerful microprocessor and has a built-in memory for 35 latest calculations.
