Application of Acrel Earth Leakage Relay in Intelligent Building
Abstract: the necessity of applying residual current relay in intelligent building is analyzed, the main functions, working principle, classification situation of ASJ residual current relay are introduced, and the principles and precautions in selecting residual current protection circuit breaker are indicated.
Keywords: ASJ residual current relay; intelligent building; application.
The residual current relay is to detect the residual current and compare the residual current value with the reference value. When the residual current value exceeds the reference value, An electrical appliance that sends out a mechanical opening and closing signal. The residual current relay is usually composed of a combined residual current protection device with low voltage circuit breaker or low voltage contactor. It is mainly suitable for TT and TN system distribution lines with rated voltage of 50 Hz, and below. It can also provide indirect contact protection for personal electric shock, so it can be widely used in intelligent building power supply and distribution system.
2.剩余电流继电器主要用途 Main uses of residual current relay
2.1 间接接触电击保护 Protection of Indirect Contact Electric Shock
间接接触电击保护的措施是自动切断电源。GB 13955“对间接接触电击事故的防护”规定：“间接接触电击事故防护的主要措施是采用自动切断电源的保护方式，以防止由于电气设备绝缘损坏发生损坏事故。当电路发生绝缘损坏造成接地故障。其故障电流值小于过电流保护装置的动作电流值时，应安装剩余电流保护装置。”研究表明，人体接触电压的安全值为 50 V。为保证人身安全，电气装置的任何部分发生绝缘故障时，一旦接触电压超过 50 V 时，需要在规定的时间内自动切断故障部分电源。过电流保护装置受电气线路和设备及自身动作值限制，不能自动切断电源。剩余电流保护装置不受负荷电流影响，可与过电流保护装置配合使用，作间接接触电击保护 。
The measure of indirect contact electric shock protection is to automatically cut off the power supply. GB 13955" the protection of indirect contact electric shock accident "stipulates :" the main measure of indirect contact electric shock accident protection is to adopt the protection mode of automatically cutting off the power supply to prevent the damage accident caused by the insulation damage of electrical equipment. When the circuit insulation damage caused by grounding fault. When the fault current value is less than the operating current value of the over-current protection device, the residual current protection device shall be installed ." According to the research, the safe value of contact voltage is 50V. For personal safety, when insulation failure occurs in any part of the electrical device, once the contact voltage exceeds 50V, it is necessary to automatically cut off the fault part of the power supply within the specified time. The over-current protection device is limited by the electrical circuit and equipment and its own action value, and can not automatically cut off the power supply. The residual current protection device is not affected by the load current and can be used in conjunction with the over-current protection device for indirect contact electric shock protection.
2.2 接地故障保护 Ground fault protection
Grounding is the contact between a live conductor and the earth, a grounded metal shell or a component connected to the ground. Its failure may lead to personal electric shock casualties and equipment damage, and may cause electrical fire in serious cases. Ground fault protection used to be protected by over-current protection device. When the grounding fault current is greater than the fixed value of the over-current protection device, the fault circuit is cut off by the over-current protection device.
In TT system, the line with larger rated current and longer distribution line, grounding fault of live conductor, unsafe metallic grounding fault and arc grounding fault in TN system may occur that the grounding fault current is less than the setting current of over-current protection action, and the over-current protection device does not act. Residual current protection device, or circuit breaker with ground fault protection, can reliably carry out ground fault protection.
2.3 电气火灾保护 Electrical fire protection
电气火灾通常由电气短路引起，电气短路包括金属性短路和电弧性短路。前者是带电导体间（如相与相之间、相与 N 线之间）短路，多以高温熔焊金属为通路，故障电流以千安计，高温易使绝缘氧化而自燃，火灾危险虽大，但可用带短路保护的断路器和熔断器保护，由断路器瞬时动作切断电源，避免火灾。后者是带电导体对地短路，多以电弧为通路，故障电流虽小，但一方面电弧长时间延续，局部温度高，很容易点燃周边可燃物质，引发火灾；另一方面，又不足以使一般断路器动作跳闸切断电源。所以电弧性短路引起火灾危险远大于金属性短路。带剩余电流动作保护功能的断路器可在过电流保护装置不动作的情况下切断保障电路，防止电弧性短路引发的电气火灾。
Electrical fire is usually caused by electrical short circuit, which includes metal short circuit and arc short circuit. The former is a short circuit between live conductors (such as between phases, between phases and N lines). The fault current is calculated in kilo ampere. High temperature is easy to cause insulation oxidation and spontaneous combustion.
Although the fire hazard is great, it can be protected by circuit breakers and fuses with short circuit protection, and the power supply is cut off by instantaneous action of circuit breaker to avoid fire. The latter is a live conductor short circuit to the ground, mostly arc as the path, although the fault current is small, but on the one hand, the arc lasts for a long time, the local temperature is high, it is easy to ignite the surrounding combustible material and cause fire. Therefore, the fire hazard caused by arc short circuit is much greater than that of metal short circuit. The circuit breaker with residual current action protection function can cut off the support circuit without the operation of the over-current protection device to prevent the electrical fire caused by the arc short circuit.
3.ASJ系列剩余电流继电器 ASJ Series of Residual Current Relay
3.1 型号和功能 Model & Function