Clase 78: Como funciona y se conecta un termostato electronico

Introduction to Electronic Thermostats

In this section, the speaker introduces electronic thermostats used in commercial refrigeration. Electronic thermostats are commonly used today due to their additional functions such as thermometer control and frost alarm.

Operation of Electronic Thermostats

• Electronic thermostats replace mechanical thermostats, frost programmers, and thermometers.

• They measure temperature using at least one temperature sensor connected to them.

• The thermostat circulates a small current through the temperature sensor to minimize self-heating effects.

• The current causes a voltage to appear on the sensor, which is measured by the thermostat.

Connection of Temperature Sensors

• When the sensor element and electronic thermostat are far apart, it is recommended to use a signal converter.

• The resistance of the connecting cable can vary with temperature, affecting the thermostat reading.

• The signal converter converts the resistance value into volts or milliamps for the thermostat input.

Voltage/Current Input for Thermostat

• The thermostat or electronic controller should have an appropriate voltage or current input based on the signal converter's output.

• Typical inputs range from 0 to 10 volts or 4 to 20 milliamps.

Features of Electronic Thermostats

This section discusses additional features of electronic thermostats such as multiple temperature probe connections and relay outputs for controlling various functions.

Multiple Temperature Probes and Relay Outputs

• Electronic thermostats can connect one or more temperature probes.

• They may have one or more contacts (relay outputs) for controlling cold production, defrost control, evaporator fans, or alarms.

Electrical Connection Diagram of Simplest Electronic Thermostat

This section explains the electrical connection diagram of a basic electronic thermostat.

Electrical Connection Diagram

• The simplest electronic thermostat has terminals for AC power supply, ambient temperature probe, and control of compressor or valve.

• It also includes terminals for configuring parameters such as set point and differential.

Set Point and Differential

This section discusses the concepts of set point and differential in electronic thermostats.

Set Point and Differential

• Unlike mechanical thermostats, electronic thermostats adjust the lowest temperature as the set point.

• The set point determines the cut-off or stop temperature of the machine.

• The highest temperature is obtained by adding the differential value to the set point.

• For example, if the set point is -26 degrees Celsius and the differential is 6, when the temperature exceeds -20 degrees Celsius, the compressor starts. When it drops below -26 degrees Celsius, it stops.

Control of Compressor with Electronic Thermostat

This section explains how an electronic thermostat controls the operation of a compressor using a room temperature probe.

Controlling Compressor Operation

• The electronic thermostat uses a room temperature probe to determine the space's cooling temperature.

• Based on the set point and differential values, it controls when to activate or deactivate the hermetic compressor.

• A relay is used to control power supply to the motor of a single-phase compressor.

Multiple Temperature Probes in Electronic Thermostat

This section discusses how an electronic thermostat can be configured with multiple temperature probes for different purposes.

Multiple Temperature Probes Configuration

• An electronic thermostat can have inputs for connecting different types of temperature probes (e.g., TC, PT1000).

• One probe measures space temperature while another is installed inside the evaporator to determine frost end.

• This configuration allows for more precise temperature control and monitoring.

The transcript provided does not cover the entire video, and some sections may be missing.

Activating the Cold Room Door

This section discusses how the cold room door is activated by an object, rather than by hand. The transcript also mentions a request with an incorporated converter.

Cold Room Door Activation

• The cold room door is not activated by hand but by an object.

• A request with an incorporated converter is shown in the image.

Controller Functionality and Temperature Measurement

In this section, the controller's functionality and temperature measurement are discussed. The transcript mentions stopping the machine, opening specific contacts, and measuring oil temperature using a probe.

Controller Functions and Temperature Measurement

• The controller stops the machine and opens contact 1, 2, and 0 to measure the oil temperature of a compressor.

• The computed contact is then passed to position 5 or 6.

• Electronic thermostats can connect one or more temperature probes and have potential-free contacts.

• Two contacts of a relay would close when its coil is activated.

• The resistance of this relay would receive 230 volts.

• Relays are used for controlling cold production and defrosting.

Connecting Temperature Probes and Potential-Free Contacts

This section explains how electronic thermostats can connect temperature probes and have potential-free contacts. It also mentions closing two contacts of a relay when its coil is activated.

Connecting Probes and Potential-Free Contacts

• Electronic thermostats can connect temperature probes and have one or more potential-free contacts.

• A relay's coil would activate the K12M coil when receiving power from neutral.

• This relay would close its two contacts.

Relay Control for Cold Production

This section discusses relays used for controlling cold production and defrosting. It mentions generating heat when the relay's coil is activated.

Relay Control for Cold Production

• Relays are used for controlling evaporator fan or generating an acoustic alarm signal.

• When the motor is stopped, a specific contact would be closed.

• When the motor is running, this contact would be open.

• The relay requires two terminals to function with AC power.

Conclusion and Call to Action

This section concludes the video and encourages viewers to like and subscribe for future tutorials. It also briefly mentions the components inside a thermostat.

Conclusion and Call to Action

• The video concludes with a thank you message and encourages viewers to like and subscribe.

• The thermostat has various components, including temperature probes, potential-free contacts, and a contact for ambient temperature measurement in the space being cooled.

Timestamps are provided in Spanish as per the transcript language.