Replacing the starting device a relay is one of the most common procedures when repairing household appliances, which allows you to bring an old refrigerator back to life without calling a technician. RKT-1 is a classic induction device installed on Soviet-made compressors, such as the DM, DH series and their modifications. Understanding the principle of its operation and the sequence of actions during installation is critically important, since incorrect assembly can lead to failure of an expensive engine.
Unlike modern solid-state analogues, induction relay RKT-1 has a simple design with a coil and a movable core that closes the starter circuit. It is this mechanical part that requires careful inspection before installation. In this article we will analyze not only the installation process itself, but also diagnostic nuances that novice technicians often miss.
Before proceeding with the physical connection, you need to make sure that the compressor itself is in good condition and the integrity of the windings. If the engine hums but does not start, or the circuit breaker trips, replacing the relay often solves the problem. However, it is worth remembering that the resource starter directly depends on the state of the voltage in the network and the frequency of unit starts.
The installation process requires a minimum set of tools, but maximum attention to detail. It is important not to confuse the contacts and correctly orient the housing relative to the compressor shaft. The RKT-1 relay has a strictly defined installation position, violation of which will make it impossible to open the starter winding after starting the engine.
The operating principle and design of the RKT-1 relay
Structurally, the device is plastic a housing containing an inductor with a movable ferrite core. When power is applied to the main winding of the motor, current flows through the relay coil, creating a magnetic field. This field pulls up the core, which mechanically closes the contacts, connecting the starting winding of the electric motor.
As soon as the compressor rotor reaches the required speed, the current in the circuit drops, the magnetic field weakens, and the core moves down under the influence of gravity. At this moment, the contacts open, turning off the starting winding, and the engine continues to operate only on the main winding. The induction principle reliable, but sensitive to spatial position.
- 🔌 Coil: creates an electromagnetic field to complete the circuit.
- ⚙️ Core: movable element that controls the contacts.
- 🔗 Contacts: copper plates that switch the starting winding.
- 🛡️ Case: dielectric protection and fastening system.
It is important to note that RKT-1 is often confused with RTP, but they have different current characteristics and dimensions. Installing the wrong model will either result in constant humming or burn out the windings. Always check the markings on the body before purchasing spare parts.
Necessary tools and preparation for work
For high-quality installation, you will need a minimum set of home craftsman. The main attention should be paid to safety, since work is carried out on electrical components, although with the power turned off. Multimeter will become your main assistant for checking the integrity of circuits.
Before starting work, the refrigerator must be completely de-energized. It is not enough to simply turn it off with a button or a regulator - be sure to unplug the cord from the outlet. This will eliminate the risk of electric shock and protect the electronics (if modern models have them when replacing adjacent components) from power surges.
☑️ Preparation for installation of RKT-1
You will need the following tools:
- 🪛 Screwdriver: flat or Phillips, depending on the type of terminal box screws.
- 🔧 Pliers: for carefully removing old terminals if they are stuck.
- 🧹 Rags and alcohol: for cleaning contacts from oxides and dirt.
- 📏 Magnifying glass: to inspect the markings on the compressor terminals.
Clean the working area around the compressor. Dust and dirt trapped inside the relay can cause short circuits or sticking of the contacts. If there are traces of oil on the compressor, they should also be removed, since the oil can corrode the plastic of the relay housing.
Removing the old starting device
Removing a faulty relay is a process that requires care. Often plastic becomes brittle over time, and careless movement can split the body or break the mounting lugs. First, remove the protective cover of the compressor terminal box by unscrewing the fixing screw or loosening the clamp.
The RKT-1 relay is placed directly on the three terminals of the compressor. It can be fixed with a spring clip or simply held in place due to a tight fit and weight. Spring clamp It is necessary to carefully bend it without using excessive force so as not to damage the tubes or wires.
⚠️ Attention: Before disconnecting the wires, be sure to photograph or sketch the connection diagram. The colors of the wires in older refrigerators may fade, and relying on them alone is dangerous.
Disconnect the wires going to the relay. They can be secured to screw terminals or simply snapped onto pins. If the terminals are oxidized, sand them with fine sandpaper until shiny. Oxides increase contact resistance, which leads to heating and eventual failure.
Remove the old relay from the compressor terminals. Do this strictly vertically upward or in the direction indicated by the design so as not to loosen the motor leads. The compressor leads are a fragile element; their failure will require expensive repairs with pipe flaring.
What to do if the relay is stuck?
If the relay cannot be removed, do not pull it by force. Gently rock from side to side, holding the body, not the wires. You can slightly warm the case with a hairdryer, but do not overheat the compressor terminals.
Connection diagram and installation procedure
The most critical stage is installing a new device. On the compressor housing, the terminals are usually marked with letters: C (Common - common), R (Run - working winding), S (Start - starting winding). In Soviet designations, these can be numbers or color marks that need to be checked with the engine passport data.
The RKT-1 relay has corresponding sockets. It is important to orient the device correctly: the inscription "Top" or the arrow on the body should face up. If you install the relay upside down, gravity will not be able to lower the core, and the starting winding will remain on, which will lead to its burnout in a few seconds.
| Compressor output | Designation | Function | Wire color (typ.) |
|---|---|---|---|
| Left lower | C |
Common (phase) | Red / Black |
| Right top | R |
Working winding | Green / White |
| Bottom right | S |
Start winding | Yellow / Blue |
| Case | GND |
Grounding | Yellow-green |
Push the relay onto the terminals until it stops. Make sure that the pins fit into the sockets tightly and without distortion. If a spring clip is used, secure it. Connect the wires to the relay terminals according to your diagram or photograph taken during the dismantling stage.
Diagnostics and typical errors
After assembly, do not rush to close the casing and put away the refrigerator. It is necessary to conduct an initial test. Plug in the unit. You should hear a click of the relay, the hum of the compressor, and after 1-3 seconds - a second click (opening of the starting winding) and a smooth hum of the running motor.
If the compressor hums, but does not start, and after a few seconds there is a loud click (activation of the heat cooler), then the starting winding does not turn on. Use a multimeter to check the integrity of the contacts inside the relay itself. It often happens that a new device has a manufacturing defect or oxidized contacts.
- ❌ Error 1: The wires of the working and starting windings are mixed up. The engine will hum and heat up.
- ❌ Error 2: The relay is installed upside down. The starting winding does not turn off.
- ❌ Error 3: Poor contact in the terminals. Causes sparking and heating.
⚠️ Attention: If the compressor starts, but after 10-20 minutes of operation the refrigerator does not cool and the tubes are warm, the problem may not be in the relay, but in a freon leak or a clogged capillary system. The relay has nothing to do with it.
Check the heating of the relay housing during operation. It may be warm, but it should not burn your hands or melt. Excessive heating indicates high contact resistance or a mismatch in the current characteristics of the motor power relay.
Safety precautions and final recommendations
Working with refrigeration equipment requires compliance with a number of safety rules. In addition to the mandatory disconnection from the network, make sure that during the installation process you do not damage the copper tubes of the cooling system. A puncture in the tube will allow refrigerant to escape and moisture to enter the system, which will require complex repairs.
Make sure that all wires are securely fastened and do not touch hot parts of the compressor or sharp edges of the housing. Vibration from a running unit can wear down the insulation over time, leading to a short circuit to the housing. Use standard clips and clamps.
After successful testing, let the refrigerator run for about an hour without load (without food). Check that the chambers are cooling evenly and that there are no extraneous vibrations. Only after making sure of stable operation can you install the protective casing and push the equipment into place.
Frequently asked questions (FAQ)
Is it possible to install an RTP relay instead of RKT-1?
In most cases, no. These relays have different current characteristics and internal structure. The RTP is designed for other starting currents. Installing the wrong relay may result in it not opening or, conversely, not being able to start the engine, which will cause overheating of the windings.
Why does the RKT-1 relay click, but the compressor does not start?
This indicates that the circuit is closed, but the engine does not receive enough impulse or is jammed. Possible reasons: low voltage in the network, an interturn short circuit in the compressor windings, jamming of the piston group or a malfunction of the relay itself (burnt contacts).
How to check the serviceability of the relay with a multimeter?
In the "up arrow" position, the resistance between the contacts should be close to zero (if the core is lifted manually or the relay designed for closure at rest, which is rare for RKT-1) or infinity. In an inverted position (imitation of operation), the circuit should open. The continuity of the coil is checked more accurately - it should not have a break.
How long does the RKT-1 relay last?
The average service life of an induction relay is 5-10 years, depending on the number of on/off cycles and the stability of the voltage in the network. Frequent power surges significantly reduce the service life of contacts.