What should be paid attention to in the installation of porcelain bottom rubber cover gate knife swi

1. Installation of porcelain bottom rubber cover gate knife switch: the bottom plate should be perpendicular to the ground during installation, and the handle should be closed upward. It cannot be installed upside down or flat, because when the blade cuts off the power supply, the blade and the clamp will produce arcs (ignition), and when the handle is closed upward, the arc will be elongated upward and easy to extinguish under the action of the electromagnetic force and rising hot air.

If it is reversed, the arc pulling effect of the hot air is just the opposite, which prevents the arc elongation from affecting the arc extinguishing, and it is easy to burn out the blade clamp. When inverted, when the gate knife is opened, due to some kind of vibration or the self-weight of the gate knife, the gate knife will automatically fall, causing a wrong closing, which will make the power-off part re-energized and affect the safety.

2. Porcelain bottom rubber cover gate knife switch wiring: the power supply should be connected to the inlet seat above the switch, and the lead wire of the motor and other loads should be connected to the outlet seat below, so that when the gate knife is opened, there will be no electric shock accident when the fuse is replaced. The screws should also be tightened when wiring, otherwise when the current passes through the wire connection, the high temperature will be generated due to the large contact resistance, which will cause the contact shrapne to "anneal" (reduce the metal hardness), cause poor contact or ignition accidents, and in serious cases, it will cause disasters and burn out the load.

In actual use, there are many accidents caused by the loosening of the contact screws and the single-phase operation of the three-phase load. Special attention should be paid to.

In the process of installation, the porcelain bottom rubber cover knife switch must pay attention to the knife connection to the load end, and the hidden electrode on it is connected to the live wire, so that when it is opened, the exposed metal part is not electrified; Generally, it should be installed vertically, and the height of the switch installation should be flat, so that it is convenient for the operator to use force, fix it on the dry wooden board, and then fix it to the wall.

There is no difference between them, the previous products are porcelain bottom knife switches, and now the base is changed to a well-insulated, fall-resistant plastic base, which has no impact on the use of the knife switch.

When the load current is less than 20A or the motor is less than 3KW, the porcelain bottom rubber cover knife switch can be selected, but the melt part should be directly connected. A fuse should be installed on the outgoing side of the switch, and the porcelain bottom rubber cover knife switch should be installed vertically.

This switch is obsolete and replaced by an air switch with a suitable capacity. There are many defects in the porcelain bottom rubber cover knife switch: the fuse is easy to loosen, and the closed fire paint screw on the porcelain handle is easy to loosen, resulting in poor contact between the knife edge of the knife switch, etc.

However, the air switch should be purchased qualified, regular, there are counterfeit on the market, ** is very cheap, and the protection effect of shoddy air opening cannot be guaranteed.

It is an obsolete product and is not recommended.

The following points must be paid attention to when selecting knife switches:

1. Press the purpose of the knife switch to select the appropriate operation mode.

2. The rated voltage and rated current of the knife switch must meet the circuit requirements.

3. Check the dynamic stability and thermal stability of the knife switch, if it is inconsistent with the circuit, the knife switch with an increased rated current should be selected.

The following points must be paid attention to when installing the knife switch:

1. The knife switch should be installed vertically, so that the operating direction of the handle during the closed operation should be closed from the bottom to the top, and the operating direction of the handle during the disconnection operation should be divided from the top to the bottom, and it is not allowed to use flat or reverse installation to prevent misclosing.

2. After the knife switch is installed, check whether the contact between the knife and the static socket is straight and tight.

3. When the bus bar is connected to the knife switch terminal, there should be no great torsional stress, and the contact is reliable. When installing the lever operating mechanism, the length of the connecting rod should be adjusted to make the knife switch operate flexibly.

The two-way knife switch is referred to as the knife switch. It consists of a porcelain base, a blade, a knife base and a bakelite cover. It is often used as a switch to isolate the power supply so that electrical equipment can be safely serviced or fused replaced.

It can also be used as a power switch for direct-start motors. When selected, the rated current of the knife switch is about three times greater than the rated current of the motor. There are still many people in our lives who do not know about the two-way knife switch and do not know its function.

In order to let you know about the two-way knife switch, I will introduce the two-way knife switch to you in detail.

Two-way knife switch

1.The structure of the two-way knife switch

1) It is composed of a porcelain base, a blade, a knife holder and a bakelite cover. It is generally used as a switch to block the power supply so that electrical equipment can be safely repaired or fuses can be replaced. It can also be used as a power switch for direct-start motors.

When selected, the rated current of the knife switch is about three times greater than the rated current of the motor. According to the number of blades, the knife switch is divided into single-pole, double-pole and three-pole.

2) The three-pole knife switch and the fuse are assembled in a box made of cast iron or steel plate, which is called an iron shell switch, and there is a handle on the side of the iron shell for operating the switch. As the name suggests, it is a kind of electrical appliance that is used in high-voltage switching appliances, as the name suggests, it is in the circuit to play a barrier effect, its own operating principle and structure are relatively simple, but because of the large amount of use, the operation reliability requirements are high, and the planning, establishment and safe operation of substations and power plants have a greater impact.

3) The primary feature of the knife switch is that it has no arc extinguishing ability, and can only open and close the circuit without load current. Primary Effect 1: After the switch is opened, a solid insulation gap is established to separate the equipment or line that needs to be repaired from the power supply with a significant disconnection point to ensure the safety of maintenance personnel and equipment.

Precautions for the installation of two-way knife switches

When installing, the bottom plate should be perpendicular to the ground, and the handle should be closed upward. It can not be reversed or flat-mounted, because when the switch knife is blocking the power supply, the blade and the clamp will arc, and the electromagnetic force of the arc and the effect of rising hot air when the handle is closed upwards will be elongated and easy to calm down. If it is reversed, the arc pulling effect of the hot air is just the opposite, which hinders the arc elongation and affects the arc extinguishing, and simply burns out the blade clamp.

When reversed, when the gate knife swings open, due to some kind of sensation or the self-weight of the gate knife, the gate knife takes the initiative to fall, resulting in a wrong closing, which will make the power failure and some re-energized, affecting the safety. The power supply should be connected to the inlet seat above the switch, and the lead wire of the load such as the motor should be connected to the outlet seat below, so that when the switch knife is opened, there will be no electric shock when the fuse is replaced.

The above is the two-way knife switch introduced to you. After reading the introduction, do you have a certain understanding of the two-way knife switch? It is recommended that you must pay attention to safety when installing the two-way knife switch, and also pay attention to the installation of the two-way knife switch, so you need to read the installation instructions carefully before installation, so as to save time and improve work efficiency.

I hope that the introduction of the two-way knife switch will be helpful for you to purchase and install the two-way knife switch.

The porcelain bottom rubber cover knife switch is a control switch commonly used in low-voltage electrical circuits in China, especially in small and medium-sized towns.

The rubber cover knife switch is the HK series open load switch (hereinafter referred to as the knife switch), which is composed of a knife and a fuse. There are two kinds of knife switches, two poles and three poles, with obvious disconnection points and short circuit protection. It is mainly used for electrical lighting circuits, electrothermal control circuits, and can also be used for the control of branch circuits, and can be used as a small asynchronous motor (below kilowatts) that is not frequently started and stopped.

Under normal circumstances, the knife switch can generally turn on and off the load rated current, so for ordinary loads, the knife switch can be selected according to the load rated current. However, when the knife switch is used to control the motor, considering that its starting current can reach 4 to 7 times of the rated current, it can not only be selected according to the rated current of the motor, but the rated current of the knife switch should be selected larger. As a rule of thumb, the rated current of the knife switch should be 3 times the rated current of the motor.

Before installation, a comprehensive inspection should be carried out on the knife switch, the contact contact should be good, no burns, the bottom of the porcelain seat and the rubber cover, the handle and the handle are not skewed, the base screw hole is tightly closed, the screws of each part are fastened, and the insulation is good. The installation site of the knife switch should be dry, dust-free and not affected by vibration.

When installing, the bottom plate of the gate knife should be perpendicular to the ground, the handle should be upward, the static contact should be located above to connect to the power supply, and the moving contact should be located below to connect to the load. In this way, when the arc generated by the circuit is cut off, the hot air rises, elongating the arc and making it easy to extinguish. At the same time, it can also avoid that when the knife switch is in the cut-off position, the movable contact of the gate knife falls freely due to gravity or vibration, and the misclosing occurs and when the gate knife is disconnected, the gate knife is not charged, and the fuse is replaced safely.

Flip-up, flat-mounted and re-mounted knives are not allowed.

The place where the inlet and outlet lines of the knife switch are connected should be tightly contacted, and the screws should be tightened. The insulated wire connected from the gate seat should not be exposed, so as not to cause electric shock. The contact between the blade and the clamp seat should not be crooked, so as to avoid improper contact or poor contact caused by the blade when it is closed into the clamp seat.

The rubber cover of the rear knife switch should be covered, and when the rubber cover is installed, the position should be corrected and not skewed. Only one bakelite screw is not allowed to be screwed on the rubber cover, and the blade should not touch the rubber cover when closing the knife.

It is clearly stipulated in the electrical installation engineering specifications that the wiring mode of various single-phase disconnectors and load switches is left fire and right zero, which is a hard requirement.

Leakage switch, a kind of switch, mainly used to prevent the occurrence of leakage accidents, when there is no leakage, the input current and the output current are equal, the vector sum of the two magnetic fluxes on the iron core is zero, and the electric potential will not be induced on the secondary winding, otherwise the voltage will be induced on the secondary winding, and the actuator will be pushed by the amplifier to trip the switch.

Answering the question of "left fire and right zero" is only a matter of habit - and it is different from the "left zero and right fire" of socket wiring, which has been written into the national standard, while the former is only a habit so far.

Why is there such a habit, or "unspoken rule"? Mainly for safety considerations - when the live wiring is live, we all know that the ** wire should be disconnected first, and when wiring, the wire should be connected to the zero line. There is a danger before the fire wire is disconnected, and after it is disconnected, it will be handled simply, so the risk factor will be greatly reduced.

Most people are left-handed, right-handed, and right-handed, (this consideration is very unfriendly to left-handers). Let's imagine two (or four) wires side by side, touching with the left hand. Touch the wires from left to right, and remove one for each contact, so that the left hand can easily touch only the target wire.

But when you start from right to left, is it easy for your left hand to touch other wires?

There are standard requirements for sockets, so that it is convenient for electrical equipment to identify the position of the live wire, so that it is convenient to add switches or take necessary safety measures on the live wire.

Air switches and leakage switches should also be manufactured according to the installation product specifications, but different manufacturers should have different products, but compared with the wiring of the socket, it is much more flexible, and the wiring is good according to the mark, otherwise the internal circuit may not work.

The wiring of the leakage switch is zero left, right, right, right, and very few electricians teach you, in fact, they are all wrong.

The teacher said that the heart is on the left side of the human body, and in terms of safety, it is better to use the left zero and right fire if it is not marked, so that when the electricity is tested, the current is introduced into the ground through the right hand.

Wiring is prescribed, but the location depends on the design. There are no fixed restrictions, just the wiring required for the connection. It is generally deliberately arranged and designed for convenience.

Household ordinary air switches are also left zero and right fire.

Look at the schematic diagram, let how to connect, the habit and reality must be based on reality

Left fire and right zero is electrical common sense

Of course, it is also best to follow such common sense for air switches

The knife switch is a manual power distribution appliance. It is mainly used to isolate the power supply or manually turn on and off AC and DC circuits, and can also be used for infrequent switching on and off loads below the rated current, such as small motors, electric furnaces, etc.

The knife switch is the most economical but the technical indicators are low. Knife switches are also known as open load switches. It mainly includes:

The moving contact knife, static contact tool holder, fuse, incoming and outgoing wiring terminal connected to the operating porcelain handle are all fixed on the porcelain base plate and covered with a rubber cover.

So when the blade is closed, the operator will not touch the live part. The plastic cover also has the following protective functions: (1) separating the poles to prevent the power supply from being short-circuited due to arcing between the poles; (2) Prevent the arc from flying out of the cover and burning the operator; (3) Prevent metal parts from falling on the gate knife to form an inter-pole short circuit.

The installation of the fuse also provides short-circuit protection function.

3) Technical parameters and selection of knife switch.

There are many types of knife switches, including two-pole (rated voltage 250V) and three-pole (rated voltage 380V), and the rated current ranges from 10A to 100A

The casing switch can only control the following motors.

Universal switch, also known as combination switch, can control the motor below 5kw, the iron switch is a load switch, different rated current can break different load current, as long as the rated current of the arc extinguishing cover and the melt is 5 times that of the motor, the motor load can be broken.