The central monitoring system of the modern solar cell production workshop building uses the Building Automation System (BA), which is closely related to the production process and safety production. Adopt DDC distributed structure, control and control of air conditioning, fresh air and ventilation system, refrigeration station system, water source system, air pressure system, gas control system, wastewater control system, pure water control system in accordance with production and management needs Wait. The central management monitoring will automatically control the power plant to work in a reasonably optimized state through the on-site controller. On the basis of highly integrated technology and highly automated production, automatic monitoring and adjustment of various equipment on the production line is an inevitable requirement of high-tech enterprises. The following is a discussion on the extraction and design of the BA contacts of the equipment field control cabinet.
2 Equipment BA contact statistics need to monitor equipment: chiller, air-cooled heat pump unit, with full heat recovery unit, cold and heat source circulating water pump, cooling tower, cooling water circulating water pump, expansion water tank, water supply bypass, air compressor station Chilled water valves, etc. The signals of the contacts can be classified into four categories: AO, DO, AI, DI. The number of points of the signal is determined according to the drawings of each professional to form a statistical table. Provide continuous control and switch control. Take the BA contact provided in the combined air conditioning control cabinet as an example. First, signal analysis should be carried out on the equipment control requirements in the construction blueprint. Count the signal type, signal control type, quantity, and so on.
Table 1 BA contact setting and signal analysis required in the electrical distribution cabinet Name Equipment Control Requirements Signal Type Signal Control Type Fan Start and Stop Contact Water Valve Power Fault Contact Combined Air Conditioner Automatic Control Contact Inverter Start and Stop Fan Variable Frequency Control Frequency Conversion Operation Feedback frequency conversion fault frequency conversion speed feedback table 1 lists the control requirements of the combined air conditioning box equipment. In the project, we refer to the fully passive contact type (ON/OFF) type as the dry ship contact input signal side contact point. The opening and closing of the dry contact in the electrical circuit outputs the working state of the electrical equipment of the switch type. The start and 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 automatic control signal of the hand is output through the remaining empty contact of the transfer switch: 420 mA signal of variable frequency feedback and control Input and output are realized directly by introducing a terminal block.
3 - The use of AC contactor to transfer the BA signal circuit design of the silane combustion tower control cabinet, where 1 and 2 fans are mutually spare, 1 and 2 corrosion-resistant pumps are mutually redundant. The coating machine of the battery sheet requires the linkage of the equipment: the galvanic combustion tower equipment does not start when the coating machine is absolutely inoperable, that is, the working state of the silane combustion tower equipment must be fed back to the battery sheet coating machine.
Since silane is a gas that burns when it encounters air, it is necessary to ensure that 1 and 2 fans cannot be simultaneously damaged in equipment safety. Similarly, 1 and 2 corrosion-resistant pumps cannot be simultaneously damaged. Under this requirement, the combination of the auxiliary contacts of the newly added KM1, KM2, KM3, and KM4 is added through the KM1, KM2, KM3, and KM4 AC contactors, and the two pumps (fans) cannot be realized. At the same time the requirements of bad (stop). The suction of the KM10, KM11, and KM12 AC contactors conveys the logic signal of the combined equipment operation to the coating machine control system. When the equipment in the normal start-up operation, any one of the loops is unreachable (because the KM1, KM2, KM3, and KM4 AC contactors are sucked), that is, the KM10, KM11, and KM12 AC contactors cannot be electrically connected in the normal state. , no signal. Only in the case that 1 and 2 fans (1 and 2 corrosion-resistant pumps) are not started at the same time, the circuit in the middle has one or two channels, KM10, KM11, KM12 AC 4 inverter cabinet transmits BA signal circuit design to domestic frequency conversion The NRB3000 model introduces the inverter and the inverter control loop. The external terminal of the standard inverter is given. The part of the BA contact inverter control principle is shown by the external terminal of the typical inverter. The input and output control of 420mA (105 and 107) (121 and 123) The signal corresponding frequency 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. In order to ensure the rapid elimination of equipment failures from the number of BA control requirements and in the event of damage to the electrical contacts, it is necessary to set up the inverter control cabinet, set some remote control contacts and provide a comprehensive control signal return contact.
(b), (163, 165) output inverter manual start/stop status feedback, (167, 169) output inverter automatic start/stop status feedback. When the signal relay 1KM is pulled in, the 1KM contact of the middle 19 (FWD) pin is closed, and the inverter starts, otherwise it stops. The self-control contact (161, 159) is the switch signal from the DDC. In the automatic state, the opening and closing of the contact directly leads to the release of 1KM, and the release of 1KM determines the stop of the inverter. (a) An AC contactor matched with the motor load current is used to form an independent control system. This circuit is not used under the normal use condition of the inverter, and is only used as a backup state when the inverter is damaged. In the circuit, the BA contact and DDC connection should also be set to achieve emergency use when the inverter is faulty.
The design provides the BA contact circuit diagram. There are two kinds of settings for the fire alarm contact. The normally open contact (NO) of the middle is connected to the control loop to achieve strong inverter or power frequency.
In many cases, to achieve a strong fire alarm, in the figure, the auxiliary normally closed contact (NC) of the signal relay is connected to the front of the automatic switch, and the coil circuit of the signal relay is connected with the functional module of the fire FA.
The BA contact setting of the soft starter is similar to the setting of the inverter, and is also realized by the connection of the signal relay and the soft starter, and will not be described. Also for various actuators or transmitters, according to the product manual, the output/input: 4~20mA DDC related terminals can be connected.
5 Substation using false B-phase current signal measurement circuit Substation's background monitoring system is generally implemented by special software and hardware. Due to the special nature of substation, only high and low voltage current, voltage, power and power are generally used. Real-time monitoring records of factors and various electrical parameters are not controlled. The technical core of the cabinet in the substation is connected to the background switch through the communication interface to form an automation system.
For the CT signal measurement circuit with error, we take the measurement loop as an example: the current transformer (2LHa) measures the A-phase current input 104 terminal, and the current transformer (2LHc) measures the C-phase current input 106 terminal. The data error is very large when the voltage is displayed by the measuring and controlling instrument, and the data sent to the switch by the measuring and controlling device through the RS485 interface is not accurate. To solve this problem, the A-phase current and the C-phase current are not combined to form a pseudo-B-phase current, and the synthesized pseudo-B-phase current is sent to the 205 terminal of the measurement and control device to form a de facto A, B, C three-phase. The current input satisfies the requirements of the meter for measuring signal input.
6 Possible methods for BA requirements before equipment ordering In industrial construction, in most cases, the supply of equipment and the installation and commissioning of equipment are not the same contractor. The installation and commissioning of the BA contact after the installation of the equipment control cabinet is often completed by the contractor of the automatic control system (weak power). When Party A orders to provide power distribution cabinets and control cabinets, it must specify the manufacturer of the electrical cabinets in the contract. In the electrical control cabinets, there must be special terminals to meet various types of BA control, and various terminal control functions are listed in the form. The function should be as comprehensive as possible to meet system connection requirements such as BA (or FA). In the control cabinet, it is often necessary to add only some signal lines, signal relays and terminal blocks. In the project, it belongs to the work interface problem of the construction. That is, the engineer of Party A must put forward the relevant wiring work interface when ordering, avoiding the temporary increase of signal lines, signal relays and terminal blocks during the construction, resulting in a large number of control lines of the power distribution cabinet. The change caused the control line to confuse and delay the construction period.
Table 2 and are echoing. Before the equipment is ordered, the BA control requirements are proposed to form the BA terminal requirements (Table 2), so that the technicians of the equipment manufacturers can accurately understand the communication requirements of the electric control cabinet equipment to the BA. Before the equipment is produced, the circuit number column in the table should be left blank for the manufacturer's technician to fill out.
7 Conclusion The method of using BA in equipment control is a trend of today, and it is widely used in the field of industrial construction. The implementation of BA control is generally completed by the contractor of the automatic control system, but the provision of the BA contact requires the engineer of Party A to submit to the equipment supplier in the form of technical requirements, and requires the manufacturer to make the contact of the BA signal before leaving the factory. To the terminal block inside the industrial control cabinet, the internal control and the external communication terminal are separated, and a friendly control cabinet communication interface is provided. Fire safety (FA) requirements should also be reflected in the table (see Table 2). Equipment control is decentralized in engineering, and the realization of automatic monitoring of equipment should be considered from the perspective of system construction. The interface between equipments is the focus of Party A engineers. After the BA (FA) contact design of the interface is completely set, the external communication of the control cabinet device can be easily completed.
The owner's engineer's attention to the BA can grasp the initiative in the construction process, avoiding the control cabinet equipment arriving after the goods. Table 2 control cabinet BA terminal requirements terminal number circuit number function brief description inverter fault status feedback inverter manual Start/stop status feedback Inverter automatic start/stop status feedback bypass automatic start/stop control bypass manual start/stop status feedback bypass automatic start/stop status feedback thermal relay fault feedback manufacturer fill in fire strong cut manufacturers fill in fire strong The manufacturer fills in the communication requirements, and a large number of changes to the control cabinet occur at the construction site.
This is both the technical method of engineering and the engineering management skills.
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