GB/T 19334-2021 in English
VALIDDimensions of low-voltage switchgear and controlgear—Standardized mounting on rails for mechanical support of switchgear,controlgear and accessories
- Issued on:2021-10-11
- Implemented on:2022-05-01
- File Format:PDF
- Delivery:Via email within 5 business days
$330.00
《GB/T 19334-2021低压开关设备和控制设备的尺寸 在开关设备和控制设备及其附件中作机械支承的标准安装轨》由TC189（全国低压电器标准化技术委员会）归口，主管部门为中国电器工业协会。
Introduction
Interpretation of the core content of the standard
GB/T19334-2021, as an equivalent adopted standard of IEC60715:2017, specifies the mechanical support requirements for TH type, C type and G type mounting rails in low-voltage switchgear. Compared with the 2003 edition, the new edition mainly strengthens:
- Requirements for protective conductor connection
- Definition of reference plane
- Improvement of tolerance system
Comparison of mounting rail types
| Type | Typical width(mm) | Installation method | Maximum torque(N·mm) | Main applications |
|---|---|---|---|---|
| TH type | 15/35/75 | Direct clip-on | 750(TH35) | Contactor, circuit breaker, etc. |
| C type | 20-50 | Accessory fixing | 20000(C50) | Modular electrical appliance combination |
| G type | 32 | Quick clamp connection | - | Centralized installation of terminal blocks |
Key technical requirements
1. Dimension tolerance system
The standard stipulates strict manufacturing tolerances:
- TH type Symmetry tolerance ≤0.2mm
- C-type railOpening width tolerance ±0.3mm
- Angular tolerance of all types of rails is unilateral limit
2. Steel rail specifications
Appendix A stipulates that cold-rolled carbon steel plates are preferred, with the following requirements:
- Tensile strength 320-420N/mm²
- Elongation ≥ 30%
- Galvanized layer thickness ≥ 6μm
Implementation points
Load calculation guide
Deflection calculation formula:
h = (ME × L × 50)/(4 × IE × G)
Where:
- ME: Equivalent torque (N·mm)
- L: Fixed point spacing (mm)
- IE: Polar moment of inertia (mm⁴)
- G: Material shear modulus (80000N/mm²)
Typical application cases
Case:A circuit breaker group with a total weight of 5kg needs to be installed in the distribution cabinet. The center of gravity is 60mm away from the guide rail surface. TH357.5 guide rail is selected:
- Calculated torque M=5×9.8×60=2940N·mm
- Based on 800mm spacing, allowable ME=120N·mm
- It is necessary to add intermediate support points to make the segment ≤400mm
Standard evolution analysis
This revision reflects three major technological trends:
- Internationalization: Completely equivalent to IEC standards, promoting international trade
- Enhanced safety: Clarify the requirements for protective conductor connection
- Improved manufacturing accuracy: Introduction of a modern tolerance marking system
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