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Today’s article is about a very useful device that I recommend installing in a home electrical panel in a private home or country house.
We are talking about a phase switch, it is also called a phase selection relay, a phase selection switch. I will call it this way and that way in the article.
I came into my hands with a real automatic three-phase phase switch PF-431 produced by Euroavtomatika F&F (Belarus), which I will thoroughly examine and dissect.
Purpose of the phase switch
In short, what is a phase switch? This is a device that analyzes the voltage quality at one of its three inputs and outputs the “best phase”. That is, (AVR) is carried out. The ideal option is to use it where there is a single-phase load, but there are 3 phases at the entrance to the building.
Moreover, for the automatic phase selection relay, it doesn’t matter which phases are at the inputs, even if it’s the same (three inputs are closed, and 1 phase of 220V is supplied to them). The input may have one or two phases. Or, for example, one from a 220V network, the second from a generator, the third from another generator!
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Read more about how one phase differs from three-phase voltage, and why there is 220V power supply and sometimes 380V.
Regarding the application with a generator, it is a great idea to use the phase switch as an automatic transfer switch (ATS). A phase has disappeared from the city - it is looking for a good phase at other inputs. The generator started (automatically or manually), the phase appeared at the second input, the relay selected the “generator” phase and switched it to home. As soon as the outdoor phase appears, the power will automatically switch to it, since it is a priority. All that remains is to figure out how to turn off the generator, but this is not a problem.
Three-phase phase switch PF-431. Appearance
Let's first consider the appearance so that the reader can imagine what we are talking about. I showed the appearance from the front panel in the photo at the beginning of the article. The device is sold in a box on which its main characteristics are briefly written:
Packaging with FiF relay parameters
The main characteristics are current, voltage, number of phases. But we will look at this in more detail in the next part of the article.
Printed on the side wall is a circuit diagram for switching on the phase switch:
Diagram on the body of the phase switch FiF PF 431
Let's look at the diagram critically. As with the FIF voltage relay, this circuit is a bit confusing. Namely, my complaints point by point:
- Three phases and zero go to terminals 1, 2, 3, 4 of the switch, and where do these wires go to the right? Is there something there? If there is, you need to sign it (for example, external consumers, load without phase selection). If there is nothing further in the diagram, then where do these wires go?
- What did the developer mean by making some lines thick? This is usually how power lines through which a large current flows are identified. Why then is the N line from input to output and the input wires not allocated? And why is the wire to control input 6 isolated, although a current of milliamps flows through it?
I’m not a bore, I just imagined that I would bring such an instruction (by the way, the instructions for the PF-431 phase switch at the end of the article) to my boss for inspection. And there will be much more points for criticism)
I will give a more detailed connection diagram and criticize it below.
This relay is mounted, like any other modular equipment, on a DIN rail.
Occupies 3 modules on a DIN rail. Or three machine guns, if that makes sense.
Control panel and indicator status
Let's look at the controls and indications on the front panel of the phase switch.
Relay control panel FiF PF 431
The most informative elements that always give out information are status indicator each of the phases:
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- extinguished – there is no phase, or the voltage is lowered below the threshold,
- lights up – phase is in use,
- flashes briefly - the phase is normal, not used,
- goes out briefly – phase is normal, recovery time is counting down,
- Blinks at a frequency of 4 times per second – phase voltage is exceeded.
If there is any problem, you need to check accident indicator:
- lights up – not a single phase meets the requirements, the outputs are disabled.
- extinguished - normal operation.
- blinking – the relay or contactor contact is stuck.
Shutdown delay control sets the time after which the phase selection relay will respond to a decrease (loss) of voltage on the operating phase. This is done for more stable and quiet operation of the relay.
The appearance is clear, but we’ll look at the insides below.
Technical characteristics of the phase switch
Now we will analyze in more detail the technical characteristics and parameters of the phase selection relay (phase switch) PF-431. Here they are:
Technical characteristics of the phase switch PF-431
Maximum permissible phase voltage – 400 V. This means that the voltage at any input can increase from 230 to 400 V. In other words, if the zero is broken and the phases are 100% unbalanced, when instead of the phase voltage a linear voltage appears at the input, the relay will not fail. This will also save the device if it is connected incorrectly, when, for example, there is one phase on L1, and another phase on N.
Supply voltage – 3x230 V, 50 Hz. That is, between the neutral (neutral) wire and any phase input for normal operation there must be 230 V.
Maximum switching current – 16 A AC1. This refers to the maximum current through the contacts of the internal relays with a purely resistive load. With a real load, which is always active-reactive, the maximum current should be less.
Maximum contactor coil current – 3 A AC15. This parameter is not entirely clear (which contactor?), meaning the contactor that will be connected for amplification (we will consider this diagram below). This also applies to any reactive load (refrigerator, air conditioner). If this current is exceeded, the phase switch will operate, but its life will be reduced.
Shutdown threshold – lower 180 V, upper 253 V. These thresholds, unlike voltage relays, are not adjustable and are set at the factory. That is, it will not work to harden the relay and supply reduced voltage to the house, if really necessary. But more about bypass below)
Reaction time – at the lower threshold 1-15 s, at the upper 0.3 s. The lower threshold can be changed using the regulator on the front panel, and the upper threshold, which is more critical, is set to a minimum and is determined by the inertia of the electrical circuit. By the way, when using a contactor, the reaction at the upper threshold will be approximately 2 times longer.
Switching time – 0.3 s. This is the time from the moment the decision to switch is made until the moment a good phase voltage appears at the output. This time can be minimal when the operating phase voltage crosses the upper threshold. Then you have to wait 0.3+0.3=0.6 seconds.
Reaction time (accelerated) at U<100B – <0,3 с, при U>300B –<0,1 с . This is the reaction time for a significantly fast and significant change in voltage. This time at the lower threshold no longer depends on the position of the regulator; at the upper threshold it is also reduced, apparently due to software solutions.
Recovery time – 10 s. This is the time after an accelerated reaction or after turning on the power required to load the program.
Hysteresis – 5 V. A useful thing that allows you to reduce the number of unnecessary relay operations when voltage fluctuations near thresholds.
I'll also tell you about switching wear resistance. It is clear that the first phase will switch the most, and the third phase the least. Therefore, it can be assumed that the first relay of the first phase will wear out faster. Also, the wear of relay contacts is significantly affected by the value and nature of the switched current.
Phase switch connection diagram
Here we come to the practical side of the issue.
Basic circuit, without contactors
The manufacturer offers the following basic connection diagram:
Basic circuit diagram for PF-431
Let's look at it in detail.
Neutral N is connected to input pin 1. It is not internally switched and is used only to power the internal circuit. This is used universally in any relays (for example, voltage relays, phase control relays, etc.) and in sensors (motion, light). That is, the neutral wire connected to terminal 1 can have a cross-section of 2.5 or 1.5 mm2, it doesn’t matter. It is important how to connect the power zero. I believe that it should not pass through this contact, otherwise it will definitely burn out, especially when using a circuit with contactors. It is best to connect the wire going to pin 1 through the bus or terminal of the input circuit breaker.
Phases L1, L2, L3, which reserve each other, are connected through terminals 2, 3, 4. It is worth saying that the apartment can be powered through the phase selection relay not completely, but only by individual single-phase consumers. Apparently, this is why the phases in the diagram go somewhere else to the right - to a three-phase load, or to a powerful load, but not critical to the quality and availability of voltage. And if one of the phases fails or there is a large imbalance, there is no point in powering a sauna with a three-phase heater or a pool pump with an asynchronous motor.
Phase power outputs – terminals 7, 9, 11. These outputs are connected together and go to the load. For example, to the introductory panel with group machines.
How can you understand from the diagram what Rн is? Some kind of load resistor? Why doesn't the instructions say anything about it? And then where to connect apartment automatic machines? These are questions from an inexperienced electrician who is looking at this circuit for the first time)
It is very important that there is a blocking of the simultaneous activation of internal relay contacts, as is done, for example, with. Otherwise, in the event of sticking of the relay contacts, or breakdown of the key transistor, or a software failure, an interphase short circuit will occur, and the consequences can be very serious, including a fire.
To prevent this from happening, a control input is provided on pin 6. It works like this. For example, input phase L1 (terminal 2) was working, but became “bad” and is turned off by an internal relay. The voltage at terminal 7, and therefore terminal 6, should disappear. If so, then the next phase is switched on. If the voltage does not disappear when the relay is turned off (for emergency reasons that I described above), then Alarm - the AL indicator starts blinking, and the emergency phase is declared faulty. After this, you need to reboot the phase switch, or repair...
Below is a wiring diagram for the phase selection relay in the form of an installation picture:
Basic diagram PF-431 installation type drawing
In this picture I tried to symbolically depict the power and low-current wires.
High current circuit on contactors
It is clear that 16A active load for a modern apartment is very little. Although, you can only connect an important load via a phase switch - boiler, internet, lighting. And feed everything else from other phases, or from the same one, but connect it to the phase switch.
But these are half measures, so there is a circuit with contactors, and the load current can now be independent of the current of the internal phase switch relays. Here is the diagram:
Circuit with contactors to amplify current
Why some wires are thick and some are not - the logic is also unclear.
Video
That's all, please ask questions and share feedback about this device in the comments!
helps improve the quality of the supplied energy resource. The use of such devices ensures reliable operation of power consumers and serves as a backup supply of electricity. The effects of voltage fluctuations are significantly reduced and uninterrupted operation of equipment and devices is guaranteed.
Device functionality
After preliminary settings, you have access to convenient voltage adjustment over a wide range from low to maximum values. Exceeding the established parameters threatens with unpleasant consequences from overheating of the internal wiring. And too low values cause frequent operation of the switches.
The unique reset time function works by checking the power supply at clearly defined periods. The return to the starting place occurs with indicators that meet the standards. In other cases, after the set time has elapsed, it starts again. This procedure ends when the required network parameters are restored.
The shutdown function is triggered as a result of the loss of voltage in all network phases. Both the first and second time ranges are configured and installed by qualified specialists.
Operating principle
Selecting the phase corresponding to the permissible indicator and connecting the load to it is the main responsibility of the device. All modern models are equipped with microcontrollers that allow the following operations:
- perform detailed voltage analysis;
- control any number of electromagnetic relays;
- display all important information on digital indicators.
In each specific case of voltage exceeding the established norms, the load automatically switches to another phase.
The digital phase switch works according to the following scheme:
- The current parameters are displayed on the indicator.
- Enabling priority load connection mode.
- After this, a transition occurs to the next phases in a situation where the established limits are exceeded.
- The time delay is adjustable to eliminate false switchings in case of a short-term voltage drop of at least 120 V.
The blinking of the indicator also indicates that the operating parameters are being exceeded. If this happens in all three phases, a complete shutdown occurs until at least one of them is restored to the desired state.
How to configure settings
You can find out the shutdown indicators based on the upper limit by pressing a button. Changing this parameter is very easy - using the “down” and “up” buttons. The next press after the first displays the lower shutdown limit. To correct this characteristic, do the following:
- priority phase mode selection;
- determination of the delay period in seconds for starting activation;
- setting the return time to the phase selected as priority;
- setting the minimum limit of 120 V switching delay time.
Proper execution of all processes will be the key to stable operation of the device. A special button is designed to reset all values with automatic selection of factory settings.
Two main groups are distinguished among the many models offered by manufacturers.
Automatic phase switch
Designed to switch to other lines in the event of disruptions in the normal operation of the current one, if it cannot fully cope with the load that has arisen. In this way, a continuous supply of voltage is ensured, which can cause equipment failure.
Installation involves installation directly next to the electric meter. Connection to the line allows for objective testing of the condition of the conductors. Voltage parameters are continuously monitored and must be strictly within the established limits.
Not only the priority one, but also the two reserve ones are constantly monitored. This guarantees a prompt transition if the need arises.
Failure to comply with the parameters specified during installation on all conductors prevents the supply of power to them. If the necessary indicators are restored on the priority line, it is connected first.
Manual phase switch
Compact devices for manually selecting the desired mode. The nuances of the work process directly depend on the quality and quantity of phase voltage.
The main criterion when choosing is the rated current parameters. The device will help you choose the optimal phase for power supply.
Application area
Both groups are equally in demand for both household and industrial equipment. Network control and protection is performed in the following cases:
- automatic components for gas boilers;
- lighting systems;
- signaling equipment;
- servers and computer networks.
Features of choice
First of all, you should understand the functional requirements at a particular site and the location of the intended installation. The huge difference lies in the specifics of operation in production and work at home.
The presence of microprocessors in an electronic machine means separate control using a sealed relay. Such a phase switch with a power from 40 to 80 A is produced in the range from inexpensive devices with a minimum set of capabilities PF-40A to modern modifications DigiTOP.
In the consumer market, both proven, reliable and simple samples and ultra-modern models are equally in demand.
Advantages and relative disadvantages
Exceptional accuracy and reliability distinguishes automatic devices. There is no danger of contacts sticking thanks to the internal locking. Voltage parameters are monitored and phase selection occurs without user intervention.
The disadvantages include the need for maximum precision in the setup and connection procedures.
Advantages of hand-held instruments:
- compactness and immunity to overloads;
- affordable price;
- unpretentiousness in work and maintenance;
- some models can be used as a switch.
The disadvantage is the need for human presence to control the devices.
The hassle associated with instability of the power supply in country houses can be easily eliminated by installing a panel with an automatic switch for switching phases and manually entering the reserve.
The supply voltage does not always meet consumer requirements. If it jumps from 220 V to 250 V, it can damage sensitive electrical appliances. A phase switch can be used as protection here.
Variety of phase switch types
Operating principle
The switch provides selection of the phase whose voltage corresponds to the set parameters. It itself is connected to a three-phase network, and at the output one of the phases is connected to the loads. If the voltage on it goes beyond the specified range, the switch switches consumers to work from another phase.
Manual phase switches
The purposes of using the devices are as follows:
- switching the power supply;
- starting and stopping electric motors, turning on transformers and other devices.
The main purpose of a mechanical switch is to create uninterruptible power supply to a single-phase load and protect consumers from power surges in the network.
The figure below shows a diagram of a 3-position rocker switch. 3 phases are connected to contacts (2), (4), (6), and a load is connected to the fixed contact.
Schematic view of 3 rocker switch positions
Manual cam switches are used for switching voltage circuits up to 380 V. They are used when turning electrical appliances on and off, as well as for creating main and control circuits. The devices are small in size, can withstand short-term overloads and have a high switching capacity. When choosing a device, it is important to pay attention to the rated current.
Many manual switch designs have a zero position in which the electrical circuits remain open. This allows them to be used as switches.
Electronic phase switches
An electronic device is better suited to protect single-phase consumers from power surges in the network. It automatically switches to another line when the existing line cannot work normally. The equipment serves to power domestic and industrial loads.
Most types of automatic device have the following installation parameters:
- Minimum and maximum voltage limits. The upper limit is especially important and should be set correctly. If it is set too low, frequent triggering will occur. At high values, the internal wiring will begin to overheat. The priority phase (L1) of the switching device is selected. If there are no voltage surges on it, the transition on lines (L2) or (L3) may not occur. If such a switch occurs, the device will continue to monitor the priority line and when the required voltage level is restored, the load will switch back. If the lower and upper voltage limits intersect within a deviation range of 10-20 V, the device will operate unstably. Therefore, it is important to make the right choice of settings.
- Reset time is the interval during which the switch must automatically check the state of the previous power source in order to return to its original state. If it is normal, the reverse transition occurs. Otherwise, the next check will occur after the same period of time. The choice of return time is made by the user, based on experience, needs and operating characteristics of the electrical network.
- Turn-on time is a pause after which the device attempts to turn on the power to the load after the voltage has disappeared in all phases.
Manufacturers
Switches "APATOR" 4G series
The Russian company “APATOR” produces products for mass use and made to special order. A wide range of products allows you to choose a suitable replacement for products from other manufacturers.
Switching schemes provide the following options:
- presence or absence of switch zero position;
- accelerated switching;
- multi-position switching with the number of poles from 1 to 8;
- group switching.
The position of the cam switch, as shown in the figure below, ensures that the electrical circuit is closed by the upper moving contacts (3) and the fixed contacts (1). The conductors are clamped with screws (12).
Diagram of the structure of a switch from the APATOR company based on a cam mechanism
When the cam (2) is turned 90 0 counterclockwise, the upper rod (5) rises upward under the action of springs and opens the circuit. The lower rod rises up together with the moving contacts, closing the lower electrical circuit.
The cam mechanism has the following advantages:
- reliable switching;
- overload resistance;
- low resistance of closed contacts;
- high speed of closing and opening contacts;
- low switching forces;
- the ability to create multiple switching schemes using the same mechanism;
- long service life.
The design of the switches makes it easy to switch electrical circuits without unnecessary pressure on the handle. It is also inappropriate to artificially slow it down.
The APATOR company manufactures special switches designed for a rated current of 100 A. High loads are ensured by duplicating contacts. The devices can be used as main switches.
SOCOMEC SCP switches
The manufacturer SOCOMEC SCP (founded in France) produces several types of devices. The most popular are multi-pole switches COMO C (mainly three- and four-pole). The devices can safely switch and switch off loads from 25 A to 100 A (Fig. a). The contact break is visible.
Various types of phase switches from SOCOMEC SCP
Sirco VM commut - a multi-pole manual switch (Fig. b) provides power to the load from two sources. The rated current is 65-125 A. When disconnected, a visible gap remains.
SIRCOVER M (fig. c) is a manually operated change-over switch with several poles. The device provides disconnection or inclusion of power supplies to the load.
Phase switch SPH-41
The device provides connection of a single-phase consumer to a three-phase four-wire network (manufactured by Vector LLC, Russia). An automatic device is installed after the meter, selects the most reliable phase in terms of parameters and connects the consumer to it. Then the voltage is monitored. The selection and setting of its upper and lower permissible limits is done in advance.
Automatic phase switching
The PEF-301 switch is shown in the figure below (manufactured by NPK Elektroenergetika LLC). The device is designed to power single-phase household and industrial loads from a three-phase network. The device automatically selects the phase with the best parameters and connects the load to it. Consumers up to 3.5 kW are connected to the network through the device (Fig. a). The priority is phase L1. When the voltage value exceeds the response threshold, PEF-301 switches the consumer to another phase using contacts (7-8), (9-10), (11-12) at the device output.
With a higher load power, the output contacts of the device are connected to the coils of magnetic starters, which control the power contacts of the voltage supply through the phase with the best characteristics (red, green and black in Fig. b).
Automatic phase switch connection diagrams
3 phase switch. Video
An overview of a three-phase switch for the home is available in the video below.
The phase switch in a house or apartment can be set manually or automatically. The electronic phase changer provides maximum comfort as it does all the work without intervention and does not require constant monitoring. You just need to properly configure its operation, and it will reliably protect household electrical appliances.
Phase switches are used to increase the reliability of power supply to single-phase consumers. The input of the phase switch is three-phase, and the output is single-phase voltage. In this article we will look at automatic and manual phase switches.
Let's say you have a three-phase input and there is a possibility that one or two phases will fail. In such cases, it is possible to make circuits that will automatically or manually switch the load to the operating phase.
Automatic switches are needed if your consumers are very sensitive to power outages, phase loss often occurs, and at rarely visited sites. For example, a country house.
Automatic phase switches.
There are different types of automatic switches.
As an example, consider the automatic phase switch PF-441.
As a rule, automatic phase switches must be used in conjunction with contactors, because The rated current of the switch contacts is only 16A. For some loads this may be quite sufficient.
PF-441 has L1 priority phase. If the voltage on phase L1 is outside the limits (190-250) V, then the phase switch switches the load from phase L1 to phase L2 or to phase L3. When voltage is restored in phase L1, it switches the load back.
But, there are phase switches that can be used without contactors: PF-40A, PF-60A, PF-80A.
The device is operational (capable of switching the load) if there is at least one phase at the input, provided that its voltage is not lower than 200 Volts (for PF-40A), or 180 Volts (for PF-60A and PF-80A).
Manual phase switches.
When looking for a manual phase changer, you need to pay attention to the required rated current. In my case, I needed a 63A switch.
The only 63A manual phase switch I could find was a 4G type cam switch. Moreover, it is not called a phase switch.
Manual phase switch diagram – 4G63-108:
From this manufacturer you can select switches with the desired switching circuit from 10 to 100A. I haven't found any other analogues. Up to 40A something else can be found.
By the way, it can be used as a manual phase switch. 2 1P switches required:
If you know of other phase switches, add them in the comments.
Consumers often think about improving the quality and reliability of network voltage, as well as protection against unexpected and dangerous outages and fluctuations in network voltage.
There is a whole class of devices designed to eliminate such problems, different methods, homemade and manual, but there are devices designed to automatically monitor all kinds of changes.
In electrical engineering there is such a thing as ATS - automatic transfer of reserve. Such devices are designed to automatically switch to a second line or backup power if the main line is de-energized.
The role of the second line can be:
- one of the phases of a three-phase network
- gasoline or diesel generator line (with auto start)
- wind generator or solar panel with charge controller and batteries
- battery with automatic charging from the network
Such a device for home implementation of such functions is called an automatic phase switch (APS)
The device has 3 inputs for connecting a three-phase network or three different voltage sources, the output to the device is single-phase, two contacts - phase and zero.
Using a mechanical relay and a special microprocessor electronic board, the device automatically determines the most suitable phase and powers its output from such a line.
What is the operating principle of the device?
In most devices, the input line is three-phase, so three phases are connected to the input (L1, L2, L3)
L1 is considered the main and priority, and the other two are backup, and if in the first phase the voltage quality deteriorates or the voltage completely disappears, the output immediately switches to another line which has the most optimal voltage quality.
Technically, such a device is not complicated; it can be repeated using relay modules, but this option will take up much more space in the electrical panel and, moreover, not all parameters can be controlled.
Secondly, the more individual parts and modules from different manufacturers, the greater the chance of the APF device as a whole not working.
It is most convenient to use a ready-made APF device.
The device operates on the principle that only one of the three relays can be turned on at a time. The device board determines priority automatically and for the consumer such switching is almost imperceptible.
As practice shows, the most popular option is a two-line APF with a variety of protection and voltage control functions. Preference is given specifically to backup power devices and an additional signal conditioning function.
In addition, there are models with a built-in voltage and indication relay on each line separately, where you can customize the maximum and minimum response thresholds.
Automatic phase switch connection diagram
The standard connection diagram is considered to be a “direct” circuit in which the output phases after the device are connected by jumpers, but the disadvantage of this option will be the power, it is limited by the power of the device (the relay built into it) and as a rule it is no more than 3.5 kW, which you will agree is very little for a large Houses.
