Standard automation of the simplest ventilation systems

General Data

The system operation provides for two start modes:

local (from electrical panel)

remote (at the operator's command from the control room from the remote control panel)

The mode is chosen the M — 0-D switch on the front panel of a board.

The system operation provides for two air treatment modes:

summer mode when air is not heated in the system

winter mode, when air is heated by water calorifer, the mode is selected by "WINTER - SUMMER" selector switch on the panel front.

The system provides for control and monitoring of the following parameters:

Supply air temperature control and control

Temperature control of return coolant by thermostat

Control of air temperature behind calorifer by thermostat

Monitoring of filter clogging by air differential pressure sensor

Check of fan operability by air differential pressure sensor

Air damper control

Control of control valve on coolant

Fan Operation Control

Sheet 1 shows the general functional diagram of the plenum ventilation unit. The plant is usually located in engineering rooms, for example in ventilation chambers, pump rooms, heat centers, etc. A combined electrical-automation shield is installed nearby. The appearance of the panel with controls and indicators is shown on sheet 2.

The plenum ventilation system contains the following elements:

1 - supply air temperature sensor (PVT3)

2 - control valve (PU2)

3 - drive of the air gate (PU1)

4 - fan

5 - filter differential pressure sensor (PVP1)

6 - fan differential pressure sensor (PVP2)

7 - thermostat of calorifer freezing threat by air (PVT1)

8 - thermostat of calorifer freezing by water (PVT2)

9 - circulation pump

The system operates in two main operating modes:

manual when R-O-A mode selector switches are set to "R" position. In this mode, the electric motors of the supply fan and circulation pump are manually switched on and off from the board using the "START" and "STOP" buttons. In manual mode, when the freezing threat thermostat operates, the supply fan is stopped and the inlet air valve is closed. Due to the design features of the air damper actuators and control valves, the latter can also be put into manual operation. Manual operation mode is used mainly during system commissioning and in emergency situations under strict control by operating personnel!

automatic mode, when R-O-A mode switches are set to "A" position, in this case all actuators operate according to controller commands.

The system provides for control and monitoring of the following parameters:

Room air temperature monitoring and control

Supply air temperature control and control

Room humidity control and control

Temperature control of return coolant by thermostat

Outside air temperature monitoring

Control of air temperature behind calorifer by thermostat

Monitoring of filter clogging by air differential pressure sensor

Serviceability check of fans by air pressure differential sensors

Control of air dampers

Control of control valve on coolant

Control of control valve on coolant

Fan Control

Humidifier Control

Note

In the considered system, it is assumed to disconnect ventilation in case of fire by means of power electrical equipment (contactor that disconnects the common power feeder of general exchange ventilation, receives a command from the fire alarm station). The backup signal for the PA1 system controller and for the dispatch system is transmitted via the information RSbus.

Sheet 1 shows the general functional diagram of the plenum ventilation unit. The plant is usually located in engineering rooms, for example in ventilation chambers, pump rooms, heat centers, etc. A combined electrical-automation shield is installed nearby.

The plenum ventilation system contains the following elements:

1 - supply air temperature sensor (PVT3)

2 - control valve (PU2)

3 - drive of the air gate (PU1)

4 - fan

5 - filter differential pressure sensor (PVP1)

6 - fan differential pressure sensor (PVP2)

7 - thermostat of calorifer freezing threat by air (PVT1)

8 - thermostat of calorifer freezing by water (PVT2)

9 - circulation pump

10 - room humidity sensor (PVT6)

11 - outdoor temperature sensor (PVT4)

12 - room air temperature sensor (PVT5)

13 - pressure drop sensor on exhaust fan (PVP3)

14 - Steam absorber pump

15 - exhaust fan

16 - control valve (PU3)

17 - drive of the air gate (PU4)

18 - drive of the air gate (PU5)

Due to the use of the freely programmable controller HPK16, the algorithm of the given supply system can be very different and carry out all possible scenarios of operation according to the selected process diagram. The specific algorithm is programmed using the INTEGRATED PLAN software. The resulting code is stored as a file on the computer and then downloaded to the ROM of the controller.

The system works as follows

After starting of fan engine (4) the actuator (3) opens the air damper - summer operation mode (selector switch on the panel is in "Summer" position). In winter mode of operation (selector switch in "Winter" position), first heating of the heater occurs, and then opening of the shutter. When the fan starts, the "Fan operation" lamp lights up.

The external air, passing through the open air damper, enters the air filter. If the pressure drop on the filter is too large, which is determined by the sensor - relay (5), then the lamp "Filter clogging" lights up on the panel. System disconnection is not provided. Sensor - relay (6) monitors the air pressure drop on the fan. If the specified pressure drop does not appear at the start of the system after a certain time interval, the system stops. The same happens if the specified pressure drop disappears during the operation of the system. At that "Supply fan accident" bulb comes ON. It continues to burn until the Alarm Reset button is pressed.

Supply air temperature sensor (1) is designed to detect air temperature in the air duct. It transmits an electrical temperature signal to the controller, which in turn controls the control valve (2) on the heater coolant. When measured temperature decreases, valve (2) opens, at increase - closes, changing coolant flow rate through calorifer and thus changing air heating in the system.

Pump (9) provides coolant circulation in the heater. It operates in the "Winter" mode and is also started together with the opening of the control valve (2) when the heater warms up or when the system stops by the signal "Threat of freezing of the heater." During pump operation "Pump operation" lamp comes ON.

Signal "Calorifer freezing threat" is generated at actuation of one of two thermostats or at actuation of both thermostats (7), (8) in "Winter" mode. In "Summer" mode - only at actuation of air thermostat (7). In this case, the "Freezing Threat" bulb lights up. Upon freezing threat signal, the following occurs:

The fan motor (4) is switched off if it has been turned on.

The circulation pump (9) is switched on if it has been turned off, regardless of the position of the switch "On - 0 - Auto" of the pump (9) and regardless of the position of the switch "Winter - Summer."

100% control valve (2) on coolant is opened.

The inlet air damper is closed due to the mechanism of spring return of the drive (3).

Electrical schematic diagram

System power is supplied through three-phase input circuit breaker QF1, which is the disconnecting and protective element for the electrical circuit of the entire system. QF2 - automatic power supply of control circuits. When the QF1 circuit breaker is switched on, the "Mains" yellow lamp illuminates on the board, indicating the presence of power supply voltage.

QF3 and QF4 - pump and fan motor circuit breakers, and KM1 and KM2 - starters of these engines.

The fan operation mode provides for local and remote control. Local control is performed by actuation of SB1 and SB2 buttons located on the board. Remote control is carried out from a console located at a distance from the board, for example in the control room. Switching from local to remote control is performed by switch SA1 (sheet 4). When the system starts, the HL7 light illuminates.

The system can operate in two modes - summer and winter. Mode switching is performed using "Winter - Summer" selector switch - SA3.

Local government, winter mode

When SB1 button is pressed, relay K4 and K5 operate. Contact K41 is a "pick-up" of button SB1. To warm up the heater, contact K43 provides a signal to time relay KT1. KT1 is responsible for the delay in time between the start of the system and the start of the fan. During this time, the 100% open valve ensures heating of the heater. After the specified time, the contact KT1 operates and turns on the fan.

Switch SA2 switches over pump control modes - "ON - 0 - AUTO." In the "ON" position, the KM2 pump contactor is activated, at that the additional contact KM21 is closed and the lamp indicating the operation of the HL6 pump is lit. The pump operates continuously. In "Automatic" mode the pump starts automatically at system start, if "Winter - Summer" selector switch is set to "Winter" position.

When one of the freezing threat thermostats operates, relay K2 operates. Contact of relay K23 bypassing switch SA2 and SA3 turns on the pump contactor. Contact K24 opens and the control valve opens 100%. Contact K21 opens the power supply circuit of contactor KM1 and stops the fan. When the thermostat operates through water or air, the relay K2 with its contact K22 turns on the relay of accident memory K3, the light bulb HL1 - "Freezing threat" lights up, which will burn constantly until the threat of freezing disappears and the button SB3 "Accident relief" is pressed.

Differential pressure sensor on filter has contact in normally open position. At filter clogging the specified contact is actuated and HL2 "Filter clogging" bulb lights on the panel. When the additional contact of the KM11 starter is closed, the lamp HL5 - the signal "Fan operation" is lit, the contact K62 of the intermediate relay K6 is closed, which together with the contact K51 is used in the control circuit to open the valve 100% during heating, and the outdoor air damper is opened, which is supplied through the contact K61. Time switch KT2 is used for generation of signal "Supply fan accident." Contact KT21 is closed if the fan does not create the required air pressure drop during a certain period of time at the start of the system. At that emergency memory relay K1 operates and light bulb HL3 "Supply fan accident" comes ON. The fan stops and the HL3 bulb will burn permanently until the SB3 "Alarm Relief" button is pressed.

Power supply voltage from QF2 circuit breaker is supplied to transformer T1 220/24 V - power supply of RKN8 controller and actuators (gate and valve actuators).

Secondary winding of 24 V transformer is protected by QF5 automatic circuit breaker. Contact K52 of relay K5 at

the system is powered on to the controller. The supply air temperature sensor is connected directly to the controller (inputs 11 - 12). Output of controller 61

generates control signal 010 (V) for proportional control of electric drive of control valve.

Summer regime

In summer mode, everything happens similarly, with the exception of the following features:

The water freezing threat thermostat is disabled to prevent its false triggers.

The temperature sensor circuit is broken, which generates a signal 0 (B) at the output of the controller, which completely closes the control valve in normal mode.

Preheating of the heater is disabled when the system starts.

The circulation pump is switched off in normal mode.

Remote control

During remote control, everything is similar to the above, except that the system is started and stopped from the remote panel by pressing SP1, SP2 buttons. When the system starts, the HLP light lights up on the remote control.

Other Automation Diagrams

The automation system of the simplest water calorifer plenum ventilation system described above can be easily modified.

The cascade controller option involves two temperature sensors. One - main - is installed either in the room (see diagram sheet 1a) or in the exhaust duct (see diagram sheet 1b). Another auxiliary sensor is installed in the supply duct and serves to limit the temperature of the supply air in reasonable aisles (usually + 14... + 35 ° С). The cascade controller allows you to more accurately monitor the temperature mode of the room in the dynamics, for example, when starting the system, while preventing the supply air temperature from going beyond the specified limits .

The cold exchanger option suggests using a controller with two outputs. The first one controls the control valve on the coolant, as in the main version.

The second output can control the remote start-up of the autonomous refrigerating machine (see diagram sheet 1c) or the control valve on the coolant. The specified modifications, as well as the connection circuits of various controllers and actuators are reflected in the electrical circuit diagrams