How to choose a DC fan chassis? In addition to the working point, the speed regulation range must also be checked
Direct answer: DC fan cabinet selection cannot only determine the equipment based on the rated air volume. In addition to the design operating point, the partial load conditions under which the system often operates must also be given, and the stability of the driver at low speed, control signal type and electrical interface must be checked. Both working conditions can be covered, and the speed regulation scheme has a foundation for implementation.
Aili Industry is discussingWhen configuring the DC fan chassis , the project is usually required to provide both design working conditions and common working conditions, and then confirm the operating range based on the matching relationship between the motor, fan and driver.
Give at least two operating conditions
The first group is the air volume and external static pressure under the maximum design demand. This set of data guarantees peak capacity and determines the basic selection of fans and motors. The second group is the part-load air volume where the system often operates. This set of data helps evaluate long-term energy consumption and also determines whether the drive is stable in low-speed areas.
For systems using differential pressure control, also specify the sensor location and differential pressure target. Whether the sensor is installed on the air duct or in the room, the control objectives will be completely different. If only 'speed adjustment is required' is written, the supplier cannot judge whether the fan can provide sufficient pressure at low speed, nor can it confirm whether the minimum speed of the driver meets the end demand.
Both operating conditions should include corresponding external static pressures. Only writing air volume without static pressure means there is no working point. The resistance of the filter section will increase with dust accumulation. The pressure difference allowed before maintenance should be used for the design working condition. Clean state or typical operating state can be used for common working conditions, but the conditions must be noted.
Check electrical configuration and mechanical conditions together
Confirm the on-site input power supply, drive installation and heat dissipation conditions, start and stop logic, speed control signals and fault feedback. It cannot be assumed that all DC fan chassis use the same analog, PWM or communication protocol. The terminal definitions of different drives may be different. Please check with the electrical diagram and terminal description before on-site wiring.
Retrofit projects also require comparison of existing flanges, foundations and control cabinet interfaces. Just because the box can be installed does not mean that the driver has space for heat dissipation, nor does it mean that the control wires can be connected to the original control cabinet. If the original system has a filter, also indicate the filter rating and expected resistance. System end configurationWhen using HEPA/ULPA high-efficiency filters , the initial resistance and resistance at the end of use of the filter should be included in the calculation of the two working conditions. When the process requirements are higher, it can be evaluatedDoes the ULPA ultra-high efficiency filter meet the requirements?
Clean room ceiling air supply can be compared simultaneouslyFFU fan filter unit ; centralized management of multiple devices can be matchedThe FFU computer group control system realizes zone speed regulation and status monitoring. Protection of single process equipment can be consideredEquipment-side fan filter unit (EFU) . The final filtered air supply at the end of the air duct can beHigh-efficiency air supply outlet (HEPA BOX) . The division of labor between these devices and the DC fan chassis should be clearly stated on the system flow chart.
Recording methods of two working conditions
Two sets of data can be listed separately in the technical list: design air volume, design external static pressure, allowable input power; common air volume, corresponding external static pressure, and expected operating hours.
The latter set of data helps evaluate long-term energy consumption, and the former set of data guarantees peak capabilities. If the two groups of working conditions are very different, it is also necessary to confirm the stability of the motor and driver at low speed. If the rotational speed drops too low, the fan may enter an unstable zone or be unable to overcome the resistance of the filter section. The minimum operating air volume should be determined by the end demand rather than the minimum speed of the drive.
From the fan law, the air volume is proportional to the rotational speed, and the shaft power is proportional to the cube of the rotational speed. The rotation speed is reduced by 20%, the air volume is reduced by approximately 20%, and the shaft power is reduced to approximately 51% of the rated value. This is the fundamental reason why speed regulation can save energy. It also means that common working conditions must fall within the range where both the fan and the driver can operate stably. If the system operates at full load for a long time, the benefits brought by speed regulation are limited; if there are obvious on-duty or partial load periods, the value of the DC solution will be reflected.
Acceptance is written as measurable conditions
It is recommended to write the air volume, static pressure, complete machine power and control actions of the two working conditions into the technical conditions. These data should be measured during acceptance and the valve opening, filter status and rotation speed should be recorded. Power figures for test conditions are missing and cannot be used for acceptance.
Aili Industrial has the supporting development capabilities for motors, fans and control systems, and can be discussed accordinglyThe DC fan chassis configuration allows the equipment performance to correspond to the actual control method. The delivery requirements should cover both design and on-duty working conditions, and verify the response after start and stop, speed regulation, alarm and disconnection. Specific structure and configuration options can be found inIt is confirmed in the fan box product catalog that non-standard projects should provide equipment or machine room drawings, and then finalize them based on the determined working points and on-site interfaces.
