Break-relay based on the widespread "breaker"

Description of the development

All this is an essential disadvantage of this thermal release. Looking ahead, I must say that the organization of remote control of these contacts allows you to replace the bimetallic plate with an ordinary one, and the current control is carried out using an electronic sensor and the corresponding key circuit. The result is a full-function release with good performance. But, this is in the future, and now consider a model designed for voltage protection devices. The current protection indicators remain the same as in the original breaker.

For tests and presentation of two experimental modifications of the break relay, two overvoltage protection devices were manufactured on the basis of a VI-TOK 3-outlet coupler, without a synchronous limiter. The photo below shows the complete set of break-relay before final assembly. As will be shown below, the relay is actual and without automatic control of resetting, that is, with one electromagnet.

Miniature electromagnets have the most economical( cost-effective) design. Magnetic cores are made of a soft galvanized strip 20x0.75 mm( suitable and container strip), the cores are made of wire d5( d6), the winding of the coil is made with a wire of 0.1 mm. Earlier it was already mentioned that the circuit of the protective device with break-relay is the most simple and reliable. It does not contain any element of increased power and no electrolytic capacitor, that is, it has the greatest resource. In standby mode, the consumption is 0.5 - 0.8 watts. Below is a photo of the internal installation of protection devices with automatic return and no auto-return, and the board of the second one, which shows well the constructive simplicity.

It was noted earlier that automatic return to the initial standby state is necessary mainly for refrigerators. Here it must be said that it is also useful for computer equipment connected to an uninterruptible power supply( for this set), and for other equipment, for example, for video surveillance systems. At the same time, auto-retrieval for TVs and other audio-video equipment is completely unnecessary. Thus, two break relay models and, respectively, the following models of protection devices are seen to be relevant:

1. Filter-splitter model with power cutoff and manual reset, and a similar model, but with auto-return.
2. Synchronous limiter( ONS) with auto-cut and manual return, and with auto-return.

Models according to claim 1, as well as the currently produced filters, are suitable only for stable city networks. It should be noted that such a model, but with a break relay, is the most economical. In it, there can be no input switch, since it is structurally simple to install a button for the breaker electromagnet, - electrical, or mechanical. Auto-return in the presented construction does not exclude a manual return - it becomes standby.

Here we should note one more positive difference between the protection devices based on the break-relay from the existing ones using a conventional relay as a release. The protection device should be designed for an input alarm voltage of up to 380 volts, since the probability of such an accident in the power grid, although low, yet always occurs, and its destructive effect is very great, the cost of losses is high. So relay protection, more precisely the scheme of this protection in existing devices is usually not designed for such a voltage( because the costs are significantly increased).Manufacturers do not give any guarantees for such a case.

The difference between break-relay is that it instantly, for 2 - 3 ms disconnects everything, that is, it works like a current machine. As for the scheme for providing auto-return, it should be said that its elements operate at currents of less than 2 - 3 mA and have sufficient voltage margin. That is, unlike the relay circuit, the heat dissipation on the elements is much smaller. Excess voltage in the input voltage control circuit is allocated by means of a classical current limiting circuit using a high-voltage low-power transistor shunted by a resistor of the order of 100 kΩ.

It should be noted that the neon indicator is used in the auto return scheme, which besides the main function is useful in that it allows documenting( an act with witnesses) to record the fact of long unacceptably high voltage in the network( to compensate for unprotected areas, including neighbors, through the court).Here it is necessary to draw the readers' attention to the fact that the issue of compensation for damage from increased voltage in the network( due to the high price of modern equipment and especially its repair) should be comprehended and studied by each consumer in advance.

The legal side of this, one might say, problem on our information requires the most serious work of the relevant departments. But, whatever the legal solutions, technical protection devices should ensure the fixation of the fact of unacceptable overstating of the voltage in the network, and the legal securing of this fact must be carried out by the expert technical service. This can obviously be done by service centers for warranty maintenance and repair of protection devices. Many modern devices have a digital voltage indicator, but in this case an expert opinion is required on the accuracy of the measurement and on the health of the protective device, that is, technical confirmation of the overvoltage. This topic is relevant and it will be useful to consider separately. Here it is necessary to finish the story about a new development - break-relay.

As before, in order of advice to the masters, it must be said that the above cut-off time was measured during tests by means of an RC chain connected to this electromagnet for this purpose. By measuring the voltage across the capacitor after the cutoff pulse and knowing the charging time constant, and also that the triggering occurs in the region of the half-wave vertex, it is possible to calculate the approximate duration of the cutoff pulse, that is, the time from the opening of the thyristor to the de-energization.

break relay tests Those who want to see the tests of the presented models can download these files:

Watch them with the sound of a normal level. During the tests of the break relay, I used a conventional transformer with volt-dummy windings and a voltage-regulating resistor, which I recommended earlier. The resistor is shunted with a triac key to provide a current pulse of electromagnets of cut-off and return( about 6 A).The button cutoff test is the same as in the synchronous limiter. The auto-return delay is counted after the voltage drop is less than the cut-off point and is a few seconds. A longer exposure requires the use of an electrolytic capacitor, an insufficiently reliable element, and an exposure of more than half an hour( for a refrigerator) also complicates the circuit.

In this respect, it should be noted that it is realistic, - without any protection devices, it is always possible the power failure for a few seconds or less( for example, due to poor contact or accidental shutdown of the general machine).Therefore, all equipment must be calculated by the manufacturers for such a power interruption. A longer delay is required only for special equipment, for example, for some refrigerators. Then it is necessary to connect them through a special time relay, which, incidentally, must be supplied by the Manufacturers themselves( than shifting it to consumers, making them acquire special protection devices).But, this is from an engineering point of view. And from the point of view of the Consumer, not limited in means, there must be, of course, the opportunity to purchase a model of a protective device with a wide range of time delay, up to the deactivation of auto-return. This is implemented, by the way, in many types of stabilizers, - with the corresponding cost and a number of shortcomings, which were mentioned earlier.

If you are interested in break-relay, you can contact for more information by mail [email protected]( Alexander Vasiliev, engineer-developer).