In an electrical forum, it was found that the circuit breaker three-pole M-type and four-pole can be inverted into the line, then the L-shaped can not fall into the line. Some people think that it is due to the breaking ability and the structure of the switch. However, this is not comprehensive. The individual here said that the circuit breaker can not be analyzed and solved. The level gauge includes dial level gauge, Float Level Gauge and Marine Glass Tube Level Gauge,Liquid level gauge, a kind of material level instrument, refers to the instrument for measuring liquid level. The level of liquid medium in the container is called liquid level. Liquid Level Meter,Self-Powered Content Gauge,Marine Tank Level Gauge,Marine Plant Level Gauge Taizhou Jiabo Instrument Technology Co., Ltd. , https://www.taizhoujbcbyq.com
I think that the circuit breaker can not be inverted into the line is restricted by the following factors:
1. Structural reasons For molded case circuit breakers, the upper line indicates that the power line passes through the link plate - static contact - moving contact - soft connection - protection system (bimetal element or heating resistor element and electromagnet system) - connection plate The lower line is the power line - connecting plate - protection system - soft connection - moving contact - static contact - connecting plate. When the line enters the line, if the short-circuit current is interrupted, although most of the arc enters the arc-extinguishing chamber, there is always a part of the charged free gas moving to the moving contact connecting portion, and the free gas of a certain phase is in contact with the adjacent phase charged body, A phase-to-phase short circuit may occur. On the other hand, even if the circuit breaker successfully breaks the short-circuit current, because the lower wiring, the protection system, the soft connection, and the common rotating shaft are always under the power supply voltage (although no current flows), the insulating member will be aged, and may also be generated. Accidents such as creepage between phases.
2. Reasons for restoring voltage The so-called recovery voltage refers to the process of breaking the short circuit of the circuit breaker and adding the voltage between the static and dynamic contacts. The arc can be extinguished as long as the arc is elongated and driven into the arc chamber, cooled, raised in arc resistance and arc voltage, and the arc voltage is greater than the recovery voltage. The recovery voltage is divided into two types: steady state recovery voltage and transient recovery voltage. The two important parameters of the transient recovery voltage are the oscillation frequency f and the over-oscillation coefficient r. The larger the f and r, the higher the voltage increase speed between the contacts, and the arc extinguishing is more difficult. The oscillation frequency f has a great relationship with the inductance, capacitance and resistance of the line. The lower incoming line has a large number of components, inductors and capacitors. The resistance is much higher than the upper feed line (the upper feed line only flows through the connecting plate and the static contact), so its transient recovery voltage is also much higher. It is difficult to extinguish the arc, often causing breakdown and re-ignition of the arc.
The high current specifications (1600A and above) and DW40/45/15HH of DW15/DW16 series circuit breakers can be used for both the incoming and outgoing lines because the contact opening distance (the opening distance of the moving and static contacts) is large. The distance between the phases is large and some insulation and insulation measures are taken. Each phase of the DW40/45/15HH is isolated by a plastic structure or forms a separate chamber, which solves the problem that the phase-to-phase short circuit and the transient recovery voltage may be large. Some molded case circuit breakers have a large margin due to the double break point or short circuit breaking capability, so they can both enter the line and enter the line.
For circuit breakers that only allow the upper line, if it is necessary to lower the line, it will only reduce the short-circuit breaking capacity. The general empirical figure is that the short-circuit breaking current Ic is 15-20% when it is less than or equal to 20KA, and it is about 25-30% when it is greater than 20KA, but different manufacturers and different types of molded case circuit breakers are used when entering the line. The ability to reduce the short-circuit breaking capacity may vary and should be in accordance with the manufacturer's technical conditions. The lower incoming line is to reduce the short-circuit breaking capability without having to reduce the wiring of the electronic residual current-operated circuit breaker (leakage circuit breaker) using current overload and short-circuit protection, and they can only be used for the incoming line. This is because the trip coil of the electronic residual current operated circuit breaker is mounted close to the load side. When the upper line enters the line, when the trip unit coil is leaking, it trips the circuit breaker because the moving and static contacts are open and the moving contacts are open. No voltage; if it is now changed to the lower incoming line, after the leakage operation occurs, the circuit breaker is opened, from the original load end (because the lower input line load end becomes the power supply end), to the trip unit coil and the moving contact Voltage, if there is a surge such as a surge in the line voltage, the coil will be burned and the residual current operated circuit breaker will lose its proper function.
The types of liquid level gauges include tuning fork vibration type, maglev type, pressure type, ultrasonic wave, sonar wave, magnetic flap, radar, etc.
The liquid level gauge is suitable for measuring and controlling the liquid level and boundary of high temperature and high pressure liquid containers. The height of liquid level is clearly indicated, the display is intuitive and eye-catching, the indicator is completely isolated from the storage tank, and has the advantages of safe use, reasonable design, simple structure, convenient and reliable installation, stable performance, long service life, low maintenance cost, easy installation and maintenance, etc.