What does the term “three-phase” mean in the three-phase standard source? Can it simply be understood as “outputting three groups of electricity simultaneously”? For those who are new to the three-phase standard source, this concept can indeed be confusing. In fact, “three-phase” describes a form of power supply and output for alternating current, not just the quantity of three output groups. It refers to three groups of alternating voltage or current with specific amplitudes, frequencies, and phase relationships. The three-phase standard source precisely controls these three groups of alternating quantities to provide the specified three-phase standard signals for electric energy measurement and related electrical tests.
In an alternating current system, “three-phase” typically refers to three alternating quantities that have a fixed relationship with each other. Three-phase voltage can be understood as A-phase, B-phase, and C-phase, which have the same frequency but phase differences from each other. This phase relationship enables a complete and continuous alternating electrical environment for the three-phase system. For the three-phase standard source, the output is not three groups of mutually independent voltages, but three-phase voltages and currents that can maintain a certain interrelationship as per testing requirements.
The “phase” in the three-phase standard source can be simply understood as the phase state of the alternating quantity. Taking a set of ideal three-phase alternating voltages as an example, the three phases have the same frequency, but the phases are sequentially different. In a conventional symmetrical three-phase system, the phases maintain a relatively stable phase relationship. However, in actual testing, it is not always required to be completely symmetrical. Some tests may require the voltage, current, or phase of a certain phase to be changed artificially. Therefore, the three-phase standard source not only needs to be able to output three signals simultaneously, but also needs to be able to control the parameters of each phase according to the testing requirements.
This is a significant difference in usage between the three-phase standard source and the single-phase standard source. The single-phase standard source mainly outputs and controls a single set of alternating voltage and current, while the three-phase standard source needs to handle three related sets of alternating quantities simultaneously. For scenarios involving three-phase energy meters, three-phase measurement devices, and related measurement tests, the three-phase standard source can directly establish the required three-phase electrical conditions, allowing the tested equipment to be tested under conditions close to the actual working state.
The LD-4SB three-phase standard source produced by HV HIPOT Electric Co., Ltd. is a device designed for such testing needs. This device uses independent control of the three-phase voltage and current circuits, and the output parameters of each phase can be adjusted separately. That is to say, “three-phase” here does not merely refer to three output terminals, but three groups that can be independently controlled with their parameters. From the output interface, LD-4SB is equipped with three-phase current output sockets I1, I2, and I3, as well as three-phase voltage output sockets U1, U2, U3, and Un, corresponding to the three-phase current and three-phase voltage outputs. This can clearly illustrate the basic structure of the “three-phase standard source”: the device simultaneously establishes three-phase voltage and three-phase current output conditions.
However, the truly important aspect of three-phase is not “having three groups of outputs”, but the ability to set and control the relationship between these three groups of outputs. The LD-4SB can not only adjust the amplitudes of three-phase voltage and current separately, but also adjust the phases and power factor of three-phase voltage and current. For tests that need to simulate different three-phase operating conditions, this control method is very important.
For example, in an ideal symmetrical test condition, the three-phase voltages typically maintain the same amplitude and output according to the specified phase relationship; while in some abnormal conditions or special tests, it may be necessary to change the voltage or current of one phase. At this time, the three-phase standard source needs to be able to adjust a certain phase individually, rather than all three phases changing together. The amplitudes of the three-phase voltage and current of LD-4SB can be adjusted separately, with adjustment accuracy including 10%, 1%, 0.1%, and 0.01%.
The “three-phase” also has a close relationship with the phase relationship. The phase adjustment range of LD-4SB is 0 to 359.99°, with a resolution of 0.01° and an accuracy of ±0.05°. This means that the three-phase standard source can change the phase relationship between different phases according to the test requirements, rather than being limited to outputting a fixed state.
In addition to the voltage phase, the current phase also affects the power parameters in the three-phase system. The power factor is actually closely related to the phase relationship between voltage and current, so the three-phase standard source often needs to control the power factor during measurement tests. The power factor adjustment range of LD-4SB is -1 to 0 to +1, with a resolution of 0.00001 and an accuracy of 0.0005.
For the three-phase standard source, the frequency of the three-phase output must also maintain a corresponding relationship. The frequency adjustment range of LD-4SB is 45Hz to 65Hz, with a resolution of 0.001Hz and an accuracy of ±0.002Hz. The device can set the output frequency according to the test conditions, providing corresponding AC signals for different test scenarios.
From an application perspective, the “three-phase” in “three-phase standard source” mainly aims to meet the testing requirements of three-phase system-related equipment. Three-phase energy meters, three-phase measurement devices, and other three-phase electrical equipment in the electric energy metering industry need to be tested under conditions where the three-phase voltage, three-phase current, and phase relationship are clear. LD-4SB is mainly used in the electric energy metering industry, electrical laboratories, and relevant departments, and can use voltage, current, frequency, phase, active power, reactive power, apparent power, and power factor as standard quantities.
Therefore, when understanding “three-phase standard source”, the focus should not be on the number “three”. What really needs to be understood is “three sets of related AC quantities”. These three sets of AC quantities have a common frequency basis, exist with a clear phase relationship, and the voltage, current, and power parameters can all be set according to the test requirements. For the standard source, this three-related relationship must also have good accuracy, stability, and repeatability.
In simple terms, “three-phase” addresses the issue of the output object and output relationship, while “standard source” addresses the issue of output accuracy and test purpose. The three-phase standard source is a testing device that can generate and control three-phase standard voltage, current, and related power parameters according to certain requirements. For users, when seeing the name “three-phase standard source”, they can focus on understanding that it can build a three-phase testing environment, rather than simply adding three output ports.
The LD-4SB three-phase standard source produced by HV HIPOT Electric Co., Ltd. adopts full digital closed-loop standard source technology. It is internally equipped with a standard power energy meter for digital closed-loop feedback, and can control the standard output of parameters such as voltage, current, frequency, phase, active power, reactive power, apparent power, and power factor.
In summary, the “three-phase” in “three-phase standard source” refers to three sets of AC voltage and current outputs with certain frequencies and phase relationships, rather than simply “three power supplies”. The three-phase standard source needs to pay attention to the amplitude, phase, and power relationship between the three phases and adjust according to different test requirements. Understanding this point makes it easier to understand why three-phase standard sources are widely used in electric energy metering, electrical experiments, and related standard testing scenarios.
Post time: Oct-09-2026