Residual current transformer is the detection element of leakage protector. Its main function is to detect the residual current (grounding fault current such as electric shock and leakage) of the main circuit passing through the transformer core, and convert the residual current of the primary circuit into the output voltage of the secondary circuit. Residual current transformer is one of the most critical components of leakage protector.
Principle of residual current transformer
The principle is based on Kirchhoff's current law: the algebraic sum of the complex current flowing into any node of the circuit is equal to zero. When the line and electrical equipment are normal, the vector sum of each phase current is equal to zero, and the secondary winding of residual current transformer has no signal output; When the vector sum of each phase current in case of grounding fault is not zero, the fault current generates magnetic flux in the annular core of residual current transformer, and the secondary winding will send a signal. When the electrical fire monitoring detector receives the signal, it will send an alarm.
What are the types of residual current transformers
There are many manufacturers, models and brands of residual current transformers in China. The main common products are:
Beijing pfeiler technology fct6200f series residual current transformer; Fujian Junhao JHA / DT series residual current transformer and jha-100a / 225A series residual current transformer;
Sandy electric sd-0.66l residual current transformer;
Schneider ma120, ia80, sa200;
Nanjing Zhending ctz-fl series residual current transformer;
Aokai electric dh-zct series residual current transformer;
Nanjing Zeming zm-lxct01 series residual current transformer;
Shanghai Leining lhy-63a, lhy-100a, lhy-160a, lhy-225a;
Guangdong Chaozhou MS electronic ddb-md series residual current transformer;
Beijing xingdongfang power klh-i, klh-ii, klh-iii;
Shanghai ankerui akh-0.66l residual current transformer, namely akh-0.66l-35, akh-0.66l-70 and akh-0.66l-105;
Hangzhou biaiqi bh-0.66l series current transformer;
Huoyuan technology hct100a-4l, hct206-lf, hct220-lf, hct215-lf, hct210-lf, hct208-lf, hct200b-lf, hct210lf;
Lbd-lct-2, lct-3 and lct-4 of longbaidi in Baoding;
Zibo Tongyue electronic 078 series residual current transformer;
Bengbu Yiai fire, Beijing Fengli Hengan ctz-fl series residual current transformers;
Beijing Huayu Xianfeng dj-lw45 series residual current transformer;
Deyang Shudian power residual current transformer;
Harbin Jiahe and Liancheng (Beijing) technology ccj70 residual current transformer;
Jh-r circular residual current transformer of Beijing Jian'an Cheng Automation Co., Ltd;
Yipukang technology SR series residual current transformer;
Hangzhou dimai technology ct-100a, ct-225a, ct-400a residual current transformer, etc.
Function of residual current transformer
The setting current of residual current transformer protection action can be from Ma level to a level, and the sensitivity is very high. Therefore, it can detect the slight change of leakage current in the electrical circuit. It is used to extract the residual current signal of the monitored line, continuously detect the leakage current of the ground system, convert the primary current with large value into the secondary current with small value through a certain transformation ratio, for protection and measurement, and realize the power monitoring of three-phase system at the same time. When leakage current occurs in the electrical circuit, it will drive the tripping device and switch the power supply network to achieve the purpose of grounding fault protection.
How to select residual current transformer (selection description)
1. Model description
Specification and parameter comparison table
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