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English
Views: 0 Author: Devin Chen Publish Time: 2025-01-07 Origin: Site
The application of high-voltage DC contactor products is becoming increasingly widespread with the development of electrification and new energy industries. And the products related to numerous application industries which have different requirements on voltages and powers. In practical applications, both manufactures and customers often have vague understanding of the term "voltage," which leads to situations where substandard products are passed off as higher-quality ones, resulting in inaccurate product matching for specific application scenarios. In severe cases, this can lead to product failure.
Take the EVQ100 product of ALQ's 750VDC series as an example (see Figure 1 below). This is the product description of the product during certification in Figure 2 below.
Figure（1）
Figure（2）
From figure (2), we can see that there are three parameters related to voltage, which are Ui that is Rated Insulation Voltage, Uimp that is Rated Impluse Withstand Voltage, and Ue that is Rated Operational Voltage. Their values are respectively:
Ui=1500V
Uimp=4kV
Ue=DC450, DC750/900/1000/1500
As it is obvious that there are three voltage-related parameters to characterize the same product. Firstly, let us learn how Ui, Uimp and Ue are defined in the IEC standard. See table (1) below.
Table（1）
Characteristic | Symbol | Explanation In IEC Standard | The Related Factor |
Rated Operational Voltage | Ue | A rated operational voltage of an equipment is a value of voltage which, combined with a rated operational current, determines the application of the equipment and to which the relevant tests and the utilization categories are referred. | Electrical endurance under Ue,Ie,DC-1 |
Rated Insulation Voltage | Ui | The rated insulation voltage of equipment is the value of voltage to which dielectric tests and creepage distances are referred. In no case shall the maximum value of the rated operational voltage exceed that of the rated insulation voltage. | The creepage distance |
Rated Impluse Withstand Voltage | Uimp | The peak value of an impulse voltage of prescribed form and polarity which the equipment is capable of withstanding without failure under specified conditions of test and to which the values of the clearances are referred.The rated impulse withstand voltage of an equipment shall be equal to or higher than the values stated for the transient over voltages occurring in the circuit in which the equipment is fitted. | The clearance |
From the table above, not only could we know the detailed definition of these three parameters, but also clearly understand the related product features and performance associated with these three parameters.
Specifically, Ue and Ie work together to achieve relevant test standards for the product in a specific usage category of DC-1, such as electrical life, indicating that the product can be arranged to operate at such voltage during the standard life period.
The Ui parameter is associated with the creepage distance characteristics of the product.
The Uimp parameter is associated with the electrical clearance characteristics of the product.
Among these three voltage parameters, Ui and Ue are the most easily confused. At the same time, in many DC applications, there are often some special industry requirements for voltages and electrical life that differ from the standards, such as the 750VDC voltage and 1000 cycles electrical life requirements in the charging pile industry.
Below, we will analyze the differences in these various voltage names using the 750VDC series EVQ100 as an example, see Table (2).
Table（2）
Voltage Type | Voltage Value | Rated Operational Current Ie | Electrical Operating Cycles | Load Type | Note | |
Rated Insulation Voltage | Ui | 1500Vdc | In accordance with standard | |||
Rated Operational Voltage | Ue | 450Vdc | 50/100/ 135A | 6000(*1) | DC-1 | In accordance with standard |
Ue | 750/900/ 1000/1500Vdc | 10A | 6000(*1) | DC-1 | In accordance with standard | |
Operating voltage | 750Vdc | 100A | 1000(*2) | Resistive | In accordance with real application but not in standard | |
Remark: | ||||||
In the market, the same specification of products from different brands may have identical Ui, but their Ue and corresponding electrical life under agreed-upon current and load types can vary significantly. Therefore, this article aims to present several voltage parameters for high-voltage DC contactors, emphasizing the distinction between Ui and Ue. Especially when reflecting a product's electrical life indicators, it is necessary to specify the exact values of voltage, current, and load type, so that it does make sense to compare electrical life parameters.
In summary, the main intention of this short document is assisting everyone in standardizing voltage terminology and accurately identifying safe and reliable high-voltage DC contactor products for use in specific work scenarios.
