When automating technological processes, various sensors and actuators are used. Both of them are in one way or another connected to controllers or input/output modules, which receive measured values ​​of physical parameters from sensors and control actuators.

Imagine that all devices connected to the controller had different interfaces - then manufacturers would have to produce a huge number of input/output modules, and in order to replace, for example, a faulty sensor, they would have to look for exactly the same one.

That is why, in industrial automation systems, it is customary to unify the interfaces of various devices.

In this article we will talk about unified analog signals. Go!

Unified Analog Signals

We deal with analog signals when measuring any physical quantities (temperature, humidity, pressure, etc.), as well as during continuous control of actuators (motor speed control using a frequency converter; temperature control using a heater, etc.). d.).

In all of the above and similar cases, analog (continuous) signals are used.

In controller equipment, in the vast majority of cases, two types of analog signals are used: a current 4-20 mA and a voltage signal 0-10 V.

Unified voltage signal 0-10 V

When using this type of signal to obtain information from a sensor, its entire (sensor) range is divided into a voltage range of 0-10 V. For example, a temperature sensor has ranges of -10...+70 °C. Then at -10 °C the sensor output will be 0 V, and at +70 °C - 10 V. All intermediate values ​​are found from proportion.

The same is true for any other device. For example, if the analog output of a frequency converter is configured to transmit the current engine rotation speed, then 0 V at its output means that the engine is stopped, and 10 V means that the engine is spinning at maximum frequency.

0-10V signal control

Using a unified voltage signal, you can not only obtain data on physical quantities, but also control devices. For example, you can bring it to the desired position, change the rotation speed of the electric motor through a frequency converter or the power of the heater.

Let’s take, for example, an electric motor whose rotational speed is controlled by a frequency converter.

The engine rotation speed is set by the controller with a 0-10 V signal arriving at the analog input of the frequency converter. The engine rotation frequency can be from 0 to 50 Hz. Then, if, in accordance with the algorithm, the controller is going to spin the motor at 25 Hz, it must supply 5V to the input of the frequency converter.

"Current loop": unified analog signal 4-20 mA

The 4-20 mA analog signal (also called the “current loop”), as well as the 0-10 V voltage signal, is used in automation to receive information from sensors and control various devices.

Compared to the 0-10 V signal, the 4-20 mA signal has several advantages:

• First, the current signal can be transmitted over longer distances compared to a 0-10V signal, which experiences a voltage drop over a long line due to the resistance of the conductors.
• Secondly, it is easy to diagnose a broken line, because the operating range of the signal starts from 4 mA. Therefore, if the input is 0 mA, it means there is a break in the line.

4-20 mA signal control

Controlling various devices using a current signal is no different from controlling them using a voltage signal. Only in this case, you need a source not of voltage, but of current.

If a device has a 4-20 mA control input, then such a device can be controlled by a controller or other intelligent device that has an appropriate output.

For example, we want to smoothly open a valve that has an electric drive with a 4-20 mA input. If you apply a current signal of 4 mA to the input, then the valve will be completely closed, and if you apply 20 mA, it will be completely open.

Active and passive analog output 4-20 mA

Often, the analog output of a sensor, controller or other device is passive, that is, it cannot be a source of current without external power. Therefore, when designing an automation circuit, you need to carefully study the characteristics of the analog outputs of the devices used, and if they are passive, add an external power source to the circuit to impregnate the current loop.

The figure shows a diagram of connecting a sensor with a 4-20 mA output to a meter-regulator with a corresponding input. Since the sensor output is passive, it requires impregnation with an external power supply.

When measuring a physical quantity (temperature, humidity, gas contamination, pH, etc.), sensors convert its value into current, voltage, resistance, capacitance, etc. (depending on the operating principle of the sensor). In order to bring the sensor output signal to a unified signal, normalizing converters are used.

Normalizing converter is a device that converts the signal of the primary converter to a unified current or voltage signal.

This is what a temperature sensor with a normalizing converter looks like:

65 nanometers is the next goal of the Zelenograd plant Angstrem-T, which will cost 300-350 million euros. The company has already submitted an application for a preferential loan for the modernization of production technologies to Vnesheconombank (VEB), Vedomosti reported this week with reference to the chairman of the board of directors of the plant, Leonid Reiman. Now Angstrem-T is preparing to launch a production line for microcircuits with a 90nm topology. Payments on the previous VEB loan, for which it was purchased, will begin in mid-2017.

Beijing crashes Wall Street

Key American indices marked the first days of the New Year with a record drop; billionaire George Soros has already warned that the world is facing a repeat of the 2008 crisis.

The first Russian consumer processor Baikal-T1, priced at $60, is being launched into mass production

The Baikal Electronics company promises to launch into industrial production the Russian Baikal-T1 processor costing about $60 at the beginning of 2016. The devices will be in demand if the government creates this demand, market participants say.

MTS and Ericsson will jointly develop and implement 5G in Russia

Mobile TeleSystems PJSC and Ericsson have entered into cooperation agreements in the development and implementation of 5G technology in Russia. In pilot projects, including during the 2018 World Cup, MTS intends to test the developments of the Swedish vendor. At the beginning of next year, the operator will begin a dialogue with the Ministry of Telecom and Mass Communications on the formation of technical requirements for the fifth generation of mobile communications.

Sergey Chemezov: Rostec is already one of the ten largest engineering corporations in the world

The head of Rostec, Sergei Chemezov, in an interview with RBC, answered pressing questions: about the Platon system, the problems and prospects of AVTOVAZ, the interests of the State Corporation in the pharmaceutical business, spoke about international cooperation in the context of sanctions pressure, import substitution, reorganization, development strategy and new opportunities in difficult times.

Rostec is “fencing itself” and encroaching on the laurels of Samsung and General Electric

The Supervisory Board of Rostec approved the “Development Strategy until 2025”. The main objectives are to increase the share of high-tech civilian products and catch up with General Electric and Samsung in key financial indicators.

0-10V control

1. What is 0-10V?

2. Why do boilers need such an entrance?

To smoothly control the power or temperature of the boiler.

3. For which boilers is this needed?

Traditionally, boilers are controlled via “dry contact”. If it is closed, then the boiler turns on and heats the coolant. If it is open, the boiler does not heat.

If the boiler has a single-stage burner, then this is the simplest, correct and only possible way to work with it.

If the boiler has a modulated burner, then you can also control it this way, but the modulation procedure itself will not work, the boiler will either work at maximum or be turned off. To control combustion modulation, various methods have been invented, incl. external signal 0-10 V.

4. Why is a modulating burner better than a single-stage one?

The single-stage will turn on and off to achieve a certain supply temperature. Very often this is usually impossible to do, so they came up with the idea of ​​​​working on hysteresis, that is, the boiler will overheat the coolant by a certain amount, after which it will go out until the coolant cools down to the desired temperature.

Thus, the boiler:

turns on and off, which leads to excess noise and some slight waste of energy in these transient processes.

overheats the coolant, which leads to slightly greater wear and tear on the heating system due to cyclical heating and cooling, as well as a slight overconsumption of energy due to increased heat loss from the boiler circuit pipes.

A modulated burner has a certain modulation depth, usually 50...80%, that is, it can reduce power up to 50...20% with reduced heat demand and constantly operate at this power without turning off and maintaining the supply temperature at a constant required level.

no transients

no coolant overheating

5. I have a boiler with a modulating burner. Do I need 0-10V control?

In simple systems there is nothing more than a boiler and radiators. In them, the boiler can often itself calculate the required supply temperature based on the outside temperature and further maintain it by changing the burner modulation, and besides, the boiler can often itself control the preparation of hot water.

If your heating system is somewhat more complex, that is, there are several circuits with different temperature conditions, for example - several floors, buildings, or there are also heated floors, a snow melter, a swimming pool, ventilation, or diverse heat sources - a cascade of boilers, a solid fuel boiler, a gas, an electric boiler at night tariff, solar collectors, heat accumulator, etc., then external automation will be needed to control this system.

External automation itself calculates what temperature is needed at what point in the system and turns on the boilers at its discretion.

Here it would be nice to be able to set the temperature or power in the boiler if it is modulating. For this, a 0-10 V signal is used.

6. Do I need to buy anything extra for the boilers?

It happens that such an entrance is in the boilers themselves, for example in DeDietrich boilers with Diematic.

It happens that there is an expansion module that needs to be placed inside the boiler or connected externally, for example the VR34 board for Vaillant boilers.

Almost all manufacturers of modulating burner boilers have models or adapters with a 0-10 V input.

7. How do boilers interpret the 0-10 V signal?

There are two modes:

setting the desired temperature, for example 1 V ⇒ 10 °C, 10 V ⇒ 100 °C

setting the burner power, for example 1 V ⇒ 10%, 10 V ⇒ 100%

Most often, you can choose one of these interpretations in the cauldron.

In SmartWeb automation you can also use both interpretations, but in other automations there is usually only one.

8. Which mode to choose - by power or by temperature?

Thus, we use completely factory algorithms of the boiler manufacturer and the temperature is the most stable.

The fact is that when controlling a cascade of boilers, it is impossible to achieve perfectly correct temperature control. With the best algorithm, it will be necessary to start the first boiler into overheating relative to the required temperature, which could be avoided by working according to power.

9. Okay, are there any alternatives to 0-10V?

There is an OpenTherm protocol, in which you can also set the boiler temperature.

Pros regarding 0-10 V control:

Boiler errors can be read

Boilers have dialects of this standard, it is not a fact that the boiler will work with your automation or that errors will be read

It is impossible to diagnose the connection because The standard is digital and there is nothing to do there without a bus analyzer. When controlling 0-10 V, a voltmeter and a battery are enough for diagnostics.

10. My boiler has a modulating burner, but there is no way to connect 0-10 V, are there other options?

For boilers with built-in weather-dependent automation and outdoor temperature sensors rated NTC5K...NTC10K, a special adapter P10 was invented, which is connected to these boilers to the terminal of the outdoor sensor, and thus you can control the boiler by temperature. Such boilers include Baxi Slim/Luna, Viessman Vitodens 100, etc.

Shipment:
- consolidated cargo PEK 2 times a week, free of charge to the terminal in St. Petersburg;
- courier delivery EMS, 4S daily (very profitable for Moscow);
- Russian Post (for only 350 rubles to anywhere in the country) daily

Delivery: from 24 hours. Depends on the region and method of transportation.

Payment: or cashless payment.

Guarantee: 12 months

Air valve drive 0-10V control.

Technical specifications briefly

This drive is a general purpose drive.

Application area:
Control of the air damper of the supply or exhaust air duct.

A drive with a 0-10V control signal is convenient to use with, which is capable of generating a 0-10V signal
on one's own. This ensures fully automatic control of the opening and closing of the damper, depending on the temperature.

This type of drive cannot be used with fire and smoke dampers.

Complete technical data for the drive

Electrical data	Rated voltage	AC220V 50-60Hz
	permissible voltage	AC 230V
	power consumption	3W when rotating 0.5W on hold
	wire cross section	0.5mm2
Functional	torque	2N*m
	valve size	up to 0.5m2
	direction of rotation	Left right
	manual redirection	not provided
	rotation angle	Max. 90 degrees, limited by mechanical stop
	opening time	<30 сек. (90град)
	noise level	45dB
	position indication	mechanical
Working conditions	protection class	3rd (safety of low-voltage equipment)
	protection level	IP54
	working temperature	-20..+50 degrees Celsius \ IEC721-3-3
	storage temperature	-30..+80 degrees Celsius \ IEC721-3-2

Dimensional characteristics of the air valve actuator