A distribution box is assembled based on electrical wiring specifications. It contains switchgear, measuring instruments, protective devices, and auxiliary equipment installed in a closed or semi-closed metal cabinet or on a panel, forming a low-voltage power distribution system. During normal operation, the circuit can be manually or automatically switched on or off. In case of malfunction or abnormal operation, the circuit can be disconnected by a protective device, or an alarm can be triggered. The measuring instruments provide real-time data on operational parameters and can also adjust certain electrical values to indicate or signal deviations from the normal working condition.
During electrical installation, wires are connected to equipment, control switches, distribution boxes, and other components. Depending on the wire’s cross-sectional area, different connection methods are used. For small-section wires, such as single-core cables like BV-3*2.5 (copper core with plastic insulation), the insulation at the end is stripped and directly crimped into the distribution box. This method doesn’t require a terminal, commonly referred to as "terminalless external wiring." On the other hand, smaller multi-strand wires, like flexible cables (BVR), which consist of multiple thin copper strands, usually need a metal sleeve—also known as a "wire nose" or terminal—to connect them to devices or switches. This is called "terminal external wiring."
For larger cross-sectional wires, typically multi-stranded, terminals must be made. These terminals come in copper or aluminum versions, matching the wire material—copper for copper conductors and aluminum for aluminum ones. This type of connection is referred to as "solder (voltage) terminal block" in budgeting terms.
Based on the current budget quota subheadings, the following conclusions can be drawn:
1. For single-core conductors with a cross-sectional area less than 6 mm², terminalless external wiring is applied. When the cross-section exceeds 6 mm², it's considered large, and the welding (voltage) terminal is used instead.
2. If the cross-section of a multi-core wire is within 6 mm², terminal external wiring is calculated. Once it exceeds this value, the welding (voltage) terminal is used.
3. The terminal material must match the wire material—copper for copper wires, aluminum for aluminum wires.
4. Once the welding (pressure) terminal is accounted for, no additional cost is allocated for terminal external wiring.
This information is essential for accurate cost estimation and proper installation practices in electrical projects. Understanding these distinctions ensures compliance with industry standards and helps avoid unnecessary expenses or errors during the construction phase.
Planar gratings are mainly used for spectrum analysis and light wavelength measurement. It is an optical device composed of a large number of parallel slits of equal width and equal distance. There are many types of gratings. The commonly used grating is made by engraving a large number of parallel notches on the glass. The nicks are divided into opaque parts, and the smooth part between the two nicks can transmit light. The exquisite grating produced by our company has thousands to tens of thousands of nicks within 1CM width, and the light passes through the grating. The resulting spectrum is the result of single-slit diffraction and multi-slit interference.
Plane Diffraction Grating,Reflective Grating,Light Grating,Optical Grating
Changchun Realpoo Photoelectric Co., Ltd. , https://www.optics-realpoo.com