Medical Care Inductive Trigger Switch
Medical Care Inductive Trigger Switch Leakage protectors have high sensitivity and quick action in response to electric shock and leakage protection. This is unmatched by other protective appliances such as fuses, automatic switches, etc. The automatic switch and fuse must pass the load current...
Medical Care Inductive Trigger Switch
Leakage protectors have high sensitivity and quick action in response to electric shock and leakage protection.
This is unmatched by other protective appliances such as fuses, automatic switches, etc. The automatic switch and fuse must pass the load current when they are normal, and their action protection value should be set to avoid the normal load current. Therefore, their main role is to cut off the phase-to-phase short circuit fault of the system (some automatic switches also have overload protection function. ). Leakage current protector utilizes the residual current of the system to react and operate. The residual current of the system during normal operation is almost zero, so the set value of its operation can be set to a very small value (usually mA level). When the system is subject to electric shock or equipment When the shell is energized, a large residual current appears, and the leakage protector operates reliably by detecting and processing this residual current to shut off the power supply.
When electrical equipment leaks, it will show an abnormal current or voltage signal. The leakage protector will detect and deal with this abnormal current or voltage signal and cause the actuator to act. We call the leakage protector based on the fault current as the current leakage protector, and the leakage protector acting as the fault voltage is called the voltage leakage protector. Due to the complex structure of the voltage-type leakage protector, poor stability due to outside interference and high manufacturing cost, it has basically been eliminated. The research and application of leakage protectors at home and abroad are dominated by current leakage protectors.
The current leakage protector is a part of the zero-sequence current in the circuit (usually referred to as residual current) as the action signal, and many electronic components as the intermediate mechanism, high sensitivity, complete functions, so this protection device is more and more widely Applications. The current leakage protector consists of four parts:
Detection element: The detection element can be described as a zero-sequence current transformer. The phase line and neutral line of the protection pass through the toroidal core, forming the primary coil N1 of the transformer, and the winding wound on the toroidal core constitutes the secondary coil N2 of the transformer. If no leakage occurs, the current flows through it. The current vector of the phase line and the neutral line is equal to zero, so the corresponding induced electromotive force cannot be generated at N2. If a leakage occurs, the current vector of the phase line and the neutral line is not equal to zero, and an induced electromotive force is generated on the N2. This signal is sent to the intermediate link for further processing.
Intermediate links: Intermediate links usually include amplifiers, comparators, and trip units. When the intermediate link is electronic, the intermediate links must also assist the power supply to provide the power required for the operation of the electronic circuit. The role of the intermediate link is to amplify and process the leakage signal from the zero-sequence transformer and output it to the actuator.
Actuator: This structure is used to receive the command signal from the intermediate link and implement the action to automatically cut off the power at the fault.
Test device: Since the leakage protector is a protective device, it should be checked regularly for its integrity and reliability. The test device is through the series connection of the test button and the current limiting resistor to simulate the leakage path to check whether the device can operate normally.