It is generally composed of two metal rods exposed in the air with a certain gap. One metal rod is connected to the power line L1 or neutral wire (N) of the protection equipment, and the other metal rod and the ground wire ( PE) is connected, when the transient over-voltage hits, the gap is broken down, and a part of the over-voltage charge is led to the earth to prevent the voltage on the protected equipment from rising. The distance between two metal rods of such a discharge gap can be adjusted as required, the structure is relatively simple, and its disadvantage is poor arc extinguishing performance. The improved discharge gap is an angular gap, and its arc extinguishing function is better than the former, and it is extinguished by the action of the electric force F of the loop and the rising action of the hot gas flow.
2. Gas discharge tube:
It is composed of a pair of cold cathode plates separated from each other and enclosed in a glass tube or ceramic tube filled with a certain inert gas (Ar). In order to increase the trigger probability of the discharge tube, there is also a triggering agent in the discharge tube. This type of gas-filled discharge tube has a diode type and a three-pole type.
The technical parameters of the gas discharge tube mainly include: DC discharge voltage Udc; impulse discharge voltage Up (normally, Up≈(2~3)Udc; power frequency withstand current In; impact withstand current Ip; insulation resistance R (>109Ω ); Electrode capacitance (1-5PF)
The gas discharge tube can be used under DC and AC conditions, and its selected DC discharge voltage Udc is as follows: Use under DC conditions: Udc≥1.8U0 (U0 is the DC voltage for normal operation of the line)
Use under AC conditions: Udc ≥ 1.44Un (Un is the AC voltage rms for normal operation of the line)
3. Varistor:
It is based on ZnO as the main component of metal oxide semiconductor nonlinear resistors, when the voltage across the two ends reaches a certain value, the resistance is very sensitive to voltage. Its working principle is equivalent to the series and parallel connection of multiple semiconductor PNs. The varistor is characterized by good nonlinearity (I = non-linear coefficient α in CUα), high through-flow capacity (～2KA/cm2), low normal leakage current (10-7～10-6A), low residual voltage (depending on In the varistor operating voltage and flow capacity), the instantaneous over-voltage response time is fast (~10-8s), no freewheeling.
The technical parameters of varistors are: varistor voltage (ie, switching voltage) UN, reference voltage Ulma, residual voltage Ures, residual voltage ratio K (K=Ures/UN), maximum flow capacity Imax, leakage current, response time .
Varistor use conditions are: varistor voltage: UN ≥ [(√ 2 × 1.2) / 0.7] U0 (U0 is the rated voltage of the power frequency)
Minimum reference voltage: Ulma ≥ (1.8 ~ 2) Uac (used under DC conditions)
Ulma ≥ (2.2 ~ 2.5) Uac (used under AC conditions, Uac is AC working voltage)
The maximum reference voltage of the varistor should be determined by the withstand voltage of the protected electronic device. The residual voltage of the varistor should be lower than the level of the damage voltage of the electronic device to be protected, ie, (Ulma)max≤Ub/K. Where K is the residual pressure ratio, Ub is the loss voltage of the protected equipment.
4. Suppression diodes:
The Suppression Diode has a clamp-limiting function. It operates in the reverse breakdown region. Because it has the advantages of low clamping voltage and fast response, it is particularly suitable for use as the last few protection elements in multistage protection circuits. The volt-ampere characteristic of the suppression diode in the breakdown region can be expressed by the following formula: I=CUα, where α is a nonlinear coefficient, and for a Zener diode α=7 to 9, an avalanche diode α=5 to 7.
2. Gas discharge tube:
It is composed of a pair of cold cathode plates separated from each other and enclosed in a glass tube or ceramic tube filled with a certain inert gas (Ar). In order to increase the trigger probability of the discharge tube, there is also a triggering agent in the discharge tube. This type of gas-filled discharge tube has a diode type and a three-pole type.
The technical parameters of the gas discharge tube mainly include: DC discharge voltage Udc; impulse discharge voltage Up (normally, Up≈(2~3)Udc; power frequency withstand current In; impact withstand current Ip; insulation resistance R (>109Ω ); Electrode capacitance (1-5PF)
The gas discharge tube can be used under DC and AC conditions, and its selected DC discharge voltage Udc is as follows: Use under DC conditions: Udc≥1.8U0 (U0 is the DC voltage for normal operation of the line)
Use under AC conditions: Udc ≥ 1.44Un (Un is the AC voltage rms for normal operation of the line)
3. Varistor:
It is based on ZnO as the main component of metal oxide semiconductor nonlinear resistors, when the voltage across the two ends reaches a certain value, the resistance is very sensitive to voltage. Its working principle is equivalent to the series and parallel connection of multiple semiconductor PNs. The varistor is characterized by good nonlinearity (I = non-linear coefficient α in CUα), high through-flow capacity (～2KA/cm2), low normal leakage current (10-7～10-6A), low residual voltage (depending on In the varistor operating voltage and flow capacity), the instantaneous over-voltage response time is fast (~10-8s), no freewheeling.
The technical parameters of varistors are: varistor voltage (ie, switching voltage) UN, reference voltage Ulma, residual voltage Ures, residual voltage ratio K (K=Ures/UN), maximum flow capacity Imax, leakage current, response time .
Varistor use conditions are: varistor voltage: UN ≥ [(√ 2 × 1.2) / 0.7] U0 (U0 is the rated voltage of the power frequency)
Minimum reference voltage: Ulma ≥ (1.8 ~ 2) Uac (used under DC conditions)
Ulma ≥ (2.2 ~ 2.5) Uac (used under AC conditions, Uac is AC working voltage)
The maximum reference voltage of the varistor should be determined by the withstand voltage of the protected electronic device. The residual voltage of the varistor should be lower than the level of the damage voltage of the electronic device to be protected, ie, (Ulma)max≤Ub/K. Where K is the residual pressure ratio, Ub is the loss voltage of the protected equipment.
4. Suppression diodes:
The Suppression Diode has a clamp-limiting function. It operates in the reverse breakdown region. Because it has the advantages of low clamping voltage and fast response, it is particularly suitable for use as the last few protection elements in multistage protection circuits. The volt-ampere characteristic of the suppression diode in the breakdown region can be expressed by the following formula: I=CUα, where α is a nonlinear coefficient, and for a Zener diode α=7 to 9, an avalanche diode α=5 to 7.
DI monitoring module is designed for the data center busway power distribution plug-in box. It is used to monitoring the circuit breaker 3 channel as a group for critical power monitoring application.
Di Monitoring Module,Di/Do Measuring Module,Digital Output Module,Dc Pv Monitoring Module
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