Self-manufacturing of a walk-through shutdown from a conventional
In electrical stores, there are switches for sale, called walk-through or mid-flight switches. Outwardly, they differ little from conventional key lighting switches. Not everyone knows that they can be used to assemble lighting control circuits, with the help of which the light can be turned on and off from two (or more) points. This may be needed in long aisles, in large rooms with multiple exits, and in other situations.
The difference between a marching switch and a conventional one
The passage apparatus consists of the same nodes as the usual one:
- grounds;
- connecting terminals (terminals);
- mobile system;
- contact group;
- decorative details: keys (maybe several) and frames.
The difference lies in the design of the contact group. A conventional key switch contains one moving contact and one fixed contact. In one position the circuit is closed, in the other open. At the through device, the contact group is changeover and consists of two fixed and one movable (changeover) contacts.In one position, one circuit is closed (the other is broken), in the other, vice versa. The second circuit is connected, the second is open. Therefore, such devices are rightly called switches.
It is not always possible to distinguish between a pass-through switch and a key device at a glance - not all manufacturers bother to mark in the form of a double arrow or a flight of stairs on the front panel. Therefore, you can determine the type of switch from the back. Feedthrough switch has at least three terminals, and a diagram of the contact group is applied on the back.
Some manufacturers, instead of the circuit, put the letter designation of the terminals on the back of the switch. One of the options: changeover contact is indicated by the letter L, fixed contacts A1 and A2. Other marking options are also possible - a single standard for designations has not been established, although the letter designation is becoming less and less common.
| Switch type | Number of keys | Terminal marking |
|---|---|---|
| Legrand Valena | 1 | Scheme |
| Lezard | 2 | Scheme |
| Makel Mimoza | 2 | Scheme |
| Champagne Simon | 2 | Letters |
Like conventional key devices, gauze switches are single-key and two-key (rarely three-key). In each case, they manage the appropriate number of contact groups.
Self-manufacturing of a pass-through switch
Marching switches are available and easy to buy. But in some cases, it may be necessary to make a pass-through switch from a conventional one. The easiest way is to use two key single-key instrument.
The input terminals must be connected with an external conductor.The first disadvantage of this method is that you will have to manipulate two keys, each time they will have to be installed in the opposite direction. The second - you will need to equip two places for installing electrical appliances. You can get rid of the second by using a two-button switch. But to turn the light on and off, you need to put both keys in opposite positions.
It is easiest to fully convert an ordinary double switch into a mid-flight switch if the contacts have a separate input. To refine it, you need to get to the contact groups and turn over one movable contact.
But most two-keyboards have a different design - with a combined input. In this case, the modification is more difficult.
Just turning over the changeover contact will not work - a long shank interferes. It will have to be cut (you can use scissors for metal, etc.). To do this, remove the entire contact system.
After that, you need to turn the movable contact 180 degrees. Since the contact pad will now be on the other side, it will be necessary to rearrange the fixed contact.
After that, you can assemble the contact system, install it in place and complete the assembly of the device.
Devices from different manufacturers may have different designs, limited only by the flight of engineering thought. For circuit breakers from other manufacturers, the conversion may be carried out in a different way (instead of cutting the busbar, it may be necessary to build it up, etc.). In each case, you need to look at the place.
After that, it is necessary to mechanically combine the two keys. You can do this with glue. If there is a suitable one-key donor, you can get a single key from it. Get a full-fledged marching switch.
The use of a pass-through device instead of a conventional one
The marching switch can be used as a regular key switch. In this case, only two contacts are involved - one movable and one fixed.
The second fixed contact is not connected anywhere. Such a scheme completely replaces a conventional device. In terms of dimensions, in most cases, also a complete match. But a marching switch is more expensive than a key switch, so such a replacement only makes sense when there is no simple key device at hand. The idea of making a switch out of a mid-flight switch is not financially rational.
How to connect a pass switch
To assemble a standard control circuit using mid-flight switches, you will need two devices. One is installed at the beginning of the corridor (or at the entrance to a room or apartment), the second - at the end point of the path (or at the end of the corridor). When analyzing the circuit, it becomes clear that it is possible to assemble or break the power circuit with any switch, regardless of the position of the second one.
Read also: How to connect a single-gang switch
For management from three or more places, an appropriate number of cross switches must be added to the circuit. Theoretically, their number is unlimited.
For those who do not understand, we recommend the video.
Features of the operation of marching vehicles
The principle of operation of the pass-through switches does not differ from the usual - in one position the light is on, in the other it is off. The difference between the marching device is that its position is uncertain. With the same state of the key, the light can be turned on or off - depending on the state of the other switch. Therefore, it is more difficult to equip them with a backlight and indication chain - the usual principle of deshunting does not work well here. Therefore, it is more difficult to buy a backlit marching switch, and the scheme of the additional chain is performed differently.
Making a pass switch from a conventional one is not too difficult. Knowing the principle of operation and the device of such a device, it can be made from an ordinary one. But disassembling, assembling and reworking the device does not increase its resource, therefore, if possible, you need to purchase a factory-made switch, and it is worth doing reworking only if there is no other way out.