The central monitoring system of the modern solar cell production plant building adopts the building automation system (BA), and the control range it involves is closely related to the production process and safety production. The DDC distributed structure is adopted to control the monitoring and control of various air conditioning, fresh air and ventilation systems, freezing station systems, water source systems, air pressure systems, gas control systems, waste water control systems, and pure water control systems in the area according to production and management needs. Wait. The central management monitoring will work through the on-site controller to automatically control the power facilities in a reasonably optimized state. It is an inevitable requirement for high-tech enterprises to automatically monitor and adjust the various equipments of the production line on the basis of highly integrated technology and highly automated production. The following discussion will be conducted on the extraction and design of the BA contacts of the equipment on-site control cabinet.
2 Equipment BA contact statistics need to monitor the equipment: chillers, air-cooled heat pump units, with full heat recovery unit, cold and hot source circulating pump, cooling tower, cooling water circulating pump, expansion tank, for the return pipe bypass, air pressure station Chilled water valve and so on. The contact signals can be classified into four major categories: AO, DO, AI, and DI. The number of points of the signal is determined according to the drawings of each professional, and a statistical table is formed. Provide continuous control and switch control. The following takes the BA contact point provided by the combined air-conditioning control cabinet as an example. The signal analysis of the equipment control requirements in the construction blueprint is firstly performed. Statistics signal type, signal control type, quantity, etc.
Table 1 Contact point setting and signal analysis required in the electrical distribution cabinet Name Equipment Control Requirements Signal Type Signal Control Type Fan Start/Stop Contact Water Valve Power Supply Failure Contact Combined Air Conditioner Hand Automatic Control Contact Frequency Converter Start/Stop Fan Frequency Conversion Control Variable Frequency Operation Feedback frequency conversion frequency conversion speed feedback Table 1 lists the control requirements of the combined air conditioning box equipment. In the project, we call the fully passive contact (ON/OFF) type the contact point of the dry ship contact input signal. The opening and closing of the dry contact in the electrical circuit will output the operating state of the electrical equipment of the switch type. The start-stop signal of the fan is output through the auxiliary contact on the AC contactor; the fault contact can be output through the auxiliary contact of the thermal relay; the hand automatic control signal is output through the remaining free contact of the transfer switch: the 420mA signal of the frequency conversion feedback and control Directly through the terminal board to achieve input and output.
3 - Use AC Contactor to Pass BA Signal Circuit Design See the control cabinet of the silane combustion tower, where 1 and 2 fans are used for each other, and 1 and 2 anti-corrosion pumps are used as backups. The requirement for the linkage of the battery film coating machine to the equipment is that the silane combustion tower equipment must not be operated when the coating film coating machine is absolutely impossible, that is, the working status of the silane combustion tower equipment must be fed back to the battery film coating machine.
Since silane is a gas that ignites when it encounters air, it is necessary to ensure that equipment 1 and 2 cannot be damaged at the same time because of the safety of the equipment. Similarly, corrosion resistant pumps 1 and 2 cannot be damaged at the same time. Under this requirement, the auxiliary contacts on the KM1, KM2, KM3, and KM4 AC contactors are added to display auxiliary combinations of the newly added KM1, KM2, KM3, and KM4 to realize that the two pumps (fans) cannot At the same time bad (stop) request. Whether the KM10, KM11, KM12 AC contactor is sucked or not supplies the coating machine control system with a logical signal of the combined device operation. In the normal start-up operation of the equipment, any one of the loops will be blocked (because the KM1, KM2, KM3, and KM4 AC contactors are engaged). In normal condition, the KM10, KM11, and KM12 AC contactors cannot be electrically connected. No signal. Only in the case of 1 and 2 fans (1 and 2 anti-corrosion pumps) did not start at the same time, the circuit in the one or two road conduction, KM10, KM11, KM12 AC 4 frequency converter cabinet pass BA signal circuit design to domestic frequency conversion NRB3000 type to introduce the inverter and frequency control loop. The standard inverter external terminal 1 is provided. The coffee supply part is the BA contact. The inverter control principle is seen through the external terminal of a typical inverter. Input and output control of 420mA (105 and 107) (121 and 123) The corresponding frequency of the signal is 0100%.109 No. 1KM contact closure can start the inverter. We can output the switching signal through other contacts (135, 137, 139) of the inverter. From the number of BA control requirements and in the event of electrical contact damage, it is absolutely necessary to set up a frequency conversion control cabinet to ensure rapid removal of equipment faults, set up some remote control contacts and provide a comprehensive control signal return contact.
In (b), (163, 165) output manual inverter start/stop status feedback, (167, 169) output inverter automatic start/stop status feedback. When the signal relay 1KM pulls, the 1KM contact before the 19 (FWD) pin is closed, and the inverter starts, otherwise it stops. The automatic control contacts (161, 159) are switching signals from the DDC. In the automatic state, the opening and closing of the contacts directly results in the release of the 1KM, and the 1KM release determines the stop of the inverter. (a) An AC contactor matched with the load current of the motor constitutes an independent control system. This circuit is not used under normal use of the inverter and is only used as backup when the inverter is damaged. In the same circuit, the BA contact and DDC connection must be set to realize emergency use when the inverter fails.
There are two kinds of settings for providing the BA contact circuit diagram. There are two types of settings for the fire contact, and the normally open contact (NO) is connected to the control circuit to achieve frequency conversion or power frequency.
In many cases, to achieve the strong fire alarm, in the figure, the auxiliary normally closed contact (NC) of the signal receiving device can be connected to the front of the hand automatic switch. The coil circuit of the signal relay is connected with the function module of the fire fighting FA.
The BA contact setting of the soft starter is similar to the setting of the inverter, and it is also realized through the connection of the signal relay and the soft starter. Also for various actuators or transmitters according to the product's instructions will be output / input: 4 ~ 20mA DDC related terminals can be connected.
5 Substations use pseudo-B-phase current signal measurement circuit Background monitoring system of substations is generally implemented with dedicated software and hardware. Due to the special nature of substations, only the current, voltage, power, and power of high and low voltages are generally used. The real-time monitoring and recording of factors and various electrical parameters is not controlled. The technical core of the cabinet in the substation is on the protection and monitoring device, and is connected to the back-end switch to form an automation system through the communication interface.
For the CT signal measurement circuit that has an error, we use the measurement loop as an example: the current transformer (2LHa) measures the phase A current input terminal 104, and the current transformer (2LHc) measures the phase C current input 106 terminal. The error of the data is very large when the measurement and control instrument displays the voltage by the two-way connection. The data sent from the measurement and control device to the switch through the RS485 interface is not accurate. To solve this problem, the phase A current and the phase C current are not combined to form a false phase B current, and the resultant false phase B current is sent to the 205 terminal of the measurement and control device to form a de facto phase A, B, and C. The current input satisfies the meter's requirement for input of measurement signals.
6 Feasible ways of requesting BA for equipment before ordering In industrial construction, in most cases, the supply of equipment is not the same as the installation and commissioning of equipment. The access and commissioning of BA contacts after the supply of equipment control cabinets is often done by the contractor of the automatic control system (weakening). When ordering to provide power distribution cabinets and control cabinets, Party A must clearly specify the manufacturer of the electrical cabinet in the contract. There must be dedicated terminals for various types of BA control in the electrical control cabinet, and list the various types of terminal control functions as a table. The function should be as comprehensive as possible to meet system connection requirements such as BA (or FA). The control cabinet often only needs to add some signal lines, signal relays and terminal boards. The work interface that belongs to the construction in the project is that the engineer of Party A must put forward the relevant wiring work interface when ordering, to avoid the temporary increase of signal lines, signal relays and terminal board during the construction of the project, resulting in a large number of control circuit of the distribution cabinet. The change caused confusion in the control line and delayed construction period.
Table 2 and are echoing. Before the equipment is ordered, BA control requirements are put forward to form the BA terminal requirements (Table 2), so that the technical personnel of the equipment manufacturer can accurately understand the communication requirements of the control cabinet equipment to the BA. Before the equipment is manufactured, the circuit number column in the table should be left blank for the manufacturer's technicians to fill in.
7 Conclusions The use of BA in equipment control is a current trend and it is widely used in industrial construction. The implementation of BA control is generally completed by the contractor of the automatic control system. However, the supply of BA contacts needs Party A's engineers to submit to the equipment supplier in the form of technical requirements. The manufacturer is required to make the BA signal contacts before leaving the factory. To the internal terminal block of the industrial control cabinet, the internal control is separated from the external communication terminal, and the friendly control cabinet communication interface is provided. The requirements for fire automation (FA) should also be reflected in the table (see Table 2). In the project, the equipment control is decentralized, and the realization of the equipment's automatic monitoring must be considered from the perspective of the system's construction. The interface between the equipments is the focus of the engineers of Party A. After the design of the BA (FA) contact point of the interface is completed, the external communication of the control cabinet device can also be easily completed.
Owner's engineers' attention to BA can grasp the initiative in the construction process and avoid the control cabinet equipment after arrival. Table 2 Control terminal BA terminal requirements Terminal number Circuit number Function Description Inverter fault status feedback Inverter Manual Start/Stop Status Feedback Frequency Inverter Auto Start/Stop Feedback Bypass Auto Start/Stop Control Bypass Manual Start/Stop Status Feedback Bypass Auto Start/Stop State Feedback Thermal Relay Fault Feedback Manufacturer Fills In Fire Stronger Manufacturer Fill In Fire Strength The manufacturer fills in the communication requirements and a large number of changes to the control cabinet take place at the construction site.
This is both a technical method of engineering and engineering management techniques.
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