Today we consider what a photo relay is. Connect it is easy, try to give a couple of tips. Let's see how to connect the photo relay, and what can prevent its proper operation.
The device and principle of operation of the photodetector
A person who understands the diagrams, after reading the subsection, will no longer need to explain how the photodetector of the FD 601 is connected. The main structural parts of any street photorelay, designed to control the level of local lighting:
- The power supply is right at the entrance. This item gives the photocell the necessary weight. The sensor is the size of a five-kopeck coin. Inside the power supply photocell is not pulsed, but the simplest. Under the cover of the photorelay a transformer lurked solid dimensions. It digests the voltage from the 220 V network into a form suitable for powering the photodiode. The entire device is a power supply for a small piece of a semiconductor the size of a nail. Now it is clear why there is a neutral wire in the photo relay: to power the primary winding of the transformer. This is not the only reason. Transformer photocell, of course, lowering. The secondary winding is relieved of the voltage required to power the photodiode.
- Rectifier in a photorelay half-wave or full-wave. In the first case, the lion's share of the voltage goes in vain. In the second - the mass of the device increases, as well as volume. And the photodiode undemanding. A lot of power photocell is not needed. The rectifier is often assembled on a single diode( no photo prefix).
- Filters in a photo relay usually smooth the input voltage ripples of 220 V. They are present for a simple reason: otherwise the transformer will start to get very hot. Sharp peaks are dangerous for inductive resistances( transformer primary).There is no output to grounding in the photorelay, inside, there is probably a similarity to the RC chain( integrator), which cuts off everything above the cut-off frequency. The second filter output. Its task is to smooth the ripple, after rectifying the voltage on the diode.
- A photodiode( light sensor) monitors the operation of a transistor or thyristor switch. Through the specified place the required voltage is applied to the base( control electrode).The valve swings open and starts supplying 220V light bulbs. Alternatively, it is acceptable to use a relay to replace the thyristor. Its shutter is controlled by a photodiode. A relay without the need to form power is expensive, and the cost of the device will grow to an unprecedented size, provoking a drop in demand for products.
- The sensor is a piece of two semiconductors of different conductivity types( electronic-n and hole-p), at the junction there is an area with a small window, where it is planned to transmit photons from the outside. Due to the action of light quanta, the p-n junction opens, a current flows. This causes the opening of the relay( key, thyristor, etc.).
Presented the whole scheme. We add that the "earth" is sometimes needed for the correct operation of the power elements( set the operating point of the non-linear element).
How the photorelay of the
is connected Actually, the picture shows an example of how to connect the photorelay. We add that, as a rule, there are three wires emanating from the housing. Purpose:
- Red - phase, leaving the lighting lamps.
- Black is a phase coming from a 220 V power supply.
- Green is ground.
A set of wires photocell can consist of other colors. For example, instead of red, brown. We'll have to read the instructions on the photo relay, it is permissible to try a straightforward method: the primary winding of the transformer should ring without difficulty. The relay may be normally open, do not pass current. The resistance of the primary winding will not be zero. Even for DC multimeter. Take a measurement and you will be able to find the ground. As for the phase, if the voltage is not applied there( the relay is normally closed), the appliance covers the device with a cover, so that the circuit goes into an incomprehensible state. We recommend in the absence of instructions just to remove the cover and see where the wires go. Phase is divided in two: the first branch will go past the key( relay, thyristor) to the output, the second will serve to power the transformer. Power supply to the end, not separated from the transformer key. The remaining wire is ground.
Look at the picture, where the authors depicted the photorelay connection circuit. All of them are of the same type, feel free to take on weapons. Weathered wire color from our example. In practice, the gamma is sometimes different, but the description becomes clear purpose.
How to choose an
photo relay Please note that each device has a range of applicability. For our case, this is the throughput capacity. The photorelay is not able to miss an infinitely large current, the power element will melt. It is important to understand that sometimes only the key will not do. The original output is the replacement of discharge and conventional lamps for LED or energy-saving. Such devices consume energy an order of magnitude less, which means that it is permissible to supply an amount 10 times more.
The lifetime of LED lamps can reach 30,000 hours. Shop Chip & Dip gives two years warranty for the goods sold of the indicated sense. Threadlike LEDs are made to imitate conventional incandescent bulbs, capable of shining for years. At the same time, they are not afraid of shaking, they are economical and relatively cheap. Neighbors will not understand that a replacement has occurred.
When a photorelay connection circuit for street lighting is formed, it is necessary to think about power and power issues. Agree, inconvenient to put a number of control keys. They spoil the appearance of the exterior, do not carry a semantic load, except to select several contours intended to turn on and off at different times. Any owner of a private household knows the facts:
- House during the development of construction acquires electrical project. You can not take and change something without a host of coordinating work. Consequently, the lower the photo relay and the effect on the circuit, the better. Then the change of incandescent or discharge bulbs to LED or energy-saving looks appropriate. The main thing is that the passed current will decrease, it will be possible to save on the relay, and also to do the only thing on the whole estate.
- The energy quota is considered an important part. According to the laws of the Russian Federation, the owner is entitled to a certain share of energy. This is called a quota. If you do not choose your share - which is already taken into account in the electrification project - then you will have to pay for what you have( !).Own quota is better to know in advance. And you can not exceed the fear of a progressive penalty. Therefore, it is advantageous to take exactly as much as the law gives. Saving energy due to external lighting allows a little more equipment to be placed inside the building.
- The energy project is manufactured by an organization with a SRO license. For execution, follow the list of works requiring permission. The law is changing annually, look for a table with construction operations that require a license. To finalize the project and insert a photo relay there is more difficult than just screwing a light bulb. In order not to conflict with the law, legal issues are clarified separately.
Pay attention when installing the photorelay, that the place of future dislocation must be able to easily penetrate the light. To adjust the switching level, a special screw is installed on the underside of the device. By adjusting its position, it is possible to freely adjust the device at the right time. Of course, a lot depends on the weather. If the morning is overcast, the light will last longer. And vice versa - when dawn is sunny, the lighting will turn off earlier.
If you don’t like it or just don’t need it, you’ll need to switch on the time relay( timer).Modern versions are distinguished by the ability to program the schedule by day of the week and select options. Sometimes rescue motion sensor. This is useful in dark galleries, where it is inefficient to turn the switches on - difficult to find. The sensor will determine that the person is approaching, and perform the necessary work.
relay How to make and connect the photo relay independently
In view of the simplicity of the design, people often want to make the photo relay independently. We are now talking about gardeners( to control the lighting), motorists and other persons who do not need the project and approval. The principle of operation of photocell has already been described above, just look at the diagram. There is a 220 V relay, it is easy to find in a microwave or a slow cooker. Choose any, if only voltage +12 V is enough to trigger.
Transistors are borrowed plain and included in the scheme with a common emitter. These are the keys unlocked by positive voltage. It is not able to enter the first cascade( located on the left) until a sufficient flux of photons of light falls on the photodiode KDF101A.Then the key simply transfers the potential to the base of the second one in the cascade of the key connecting the circuit earth to the relay. Thus, the circuit closes. And the 12 V voltage to the control electrode of the power relay begins to flow to the full.
A diode connected in parallel with the relay serves to recapture when the transistors close. Pay special attention to the experimentally selected value of the resistor, which determines the modes of operation of both transistors. It is required simply to select the correct point by the current-voltage characteristic. Then calculate how to share the voltage. Note that the power is taken directly through the relay. If the circuit diagram does not allow you to do this, you will have to pass the power wire directly to the photodiode cathode, you can use another relay. Otherwise, the scheme will not work.
By the way, it is possible to test the photo relay in minutes using an ordinary multimeter. The wiring diagram for the street light photoelectric switch is similar to that described above. A voltage of +12 V can be taken from any power supply that is nearby( or a battery).