How to adapt the original start-stop circuit after replacing the old air-conditioning box with a DC fan?

After replacing the old air conditioning box with a DC fan, the original start and stop commands, power loop, speed regulation, operation feedback and protection relationship should be rechecked. Just because the original controller can control a motor does not mean that it can directly drive the fresh air blower; the power supply and start-stop requirements for integrated drive products must be based on the specific model data.

Use the old and new interface comparison table to identify the parts that need to be changed

List whether the original system is contactor start and stop, frequency conversion control or other forms, and then compare it with the enable and speed commands required by the new fan. The definition of the original fault contact, thermal protection or operating signal may also change. The multi-wind turbine solution also needs to explain the handling of a single unit failure, and it is not appropriate to simply combine all feedback into a signal that cannot be located.

The original system needs to write the command type, power supply, speed regulation and existing interlocking; the new equipment needs to write the input requirements, enablement, feedback and failure status; the adaptation work needs to write the interface conversion, program modification and protection verification scope. The three types of information correspond to different transformation stages and cannot only compare motor power. What driving conditions need to be matched when using a DC fan in an air-conditioning box? Please refer toWhat driving conditions need to be matched when using a DC fan in an air-conditioning box?。

First confirm the form of the original start-stop circuit

Common forms of fan start-stop circuits in old air-conditioning boxes include: contactor direct start-stop, star-delta start, soft starter, and inverter control. Different forms correspond to different amounts of transformation work. The circuit modification of direct start and stop of the contactor is relatively simple, but it still needs to be confirmed whether the fresh air blower requires an enabling signal and a speed regulation signal. The loop controlled by the inverter may need to adjust parameters or replace the control board.

It also needs to be checked whether the original circuit has a thermal relay, overcurrent protection, phase loss protection and emergency stop circuit. The new air blower may come with over-temperature, over-current and stall protection, but the protection logic of the original system should still be retained or redesigned.

The power loop and signal loop should be checked separately.

The power circuit includes supply voltage, phase number, current and protection devices. A DC fan with an integrated drive may be connected to an AC power supply or a DC power supply, and its input current and starting current characteristics are different from those of the old motor. The signal loop includes start and stop commands, enable signals, speed regulation signals and running feedback. The signal type and level of the original controller may not match the new fan.

Just because the original control cabinet can start the old motor does not mean that it can start the new fan directly. The fresh air blower may require an independent enable signal, communication command or 0-10V speed regulation signal. The power loop and signal loop should be drawn separately and checked point by point.

Start-stop logic and protection interlocking need to be re-verified

The start-stop logic of the old system may match the characteristics of the old motor, such as start delays, contactor retention and thermal protection reset. Fresh air fans may require different start sequences or enabling conditions. The antifreeze protection, electric heating interlock and fan failure handling of the original system also need to be re-verified under the new logic.

For control point table and signal definition, please refer toWhat point tables need to be provided before the air-conditioning box is connected to the building automation system? . The difference between BACnet interface and dry contact, please refer toWhat is the difference between the BACnet interface and dry contact linkage of the air conditioning box? . How to define the Modbus register, please refer toWhat register information should be specified in Modbus communication of air conditioning box?。

Multi-fan solutions need to be managed one by one

If the old unit has multiple fans and is replaced with a DC fan, each fan may require independent enablement and feedback. Simply connecting multiple fans in parallel to one start and stop command may not be able to locate a single fault. Please refer to the group control planThe supporting ideas of the FFU computer group control system clarify the relationship between a single unit failure and the overall operation.

How to calculate fan energy consumption by time, please refer toHow to calculate the energy consumption of air conditioning box fans separately according to operating periods? . The apportionment method when multiple wind turbines share an electric meter should also be stated in the renovation plan.

What should be covered by post-retrofit verification?

Qualified electrical and control personnel shall implement it according to the confirmed drawings, verify local remote control, start and stop, speed regulation, fault and power outage recovery, and check relevant heating and humidification permission conditions. The original logic that has not been verified cannot be used directly, and the transformation cannot be judged to be completed just because the fan has rotated. Final wiring and program versions should be documented.

For condition checks before starting the machine for the first time, please refer toWhat conditions need to be checked before the air conditioner is turned on for the first time? . How to change the debugging sequence from stand-alone to system linkage, please refer toHow to change the debugging sequence of air conditioning box from stand-alone unit to system linkage? . For troubleshooting when the fan is running but there is no obvious air supply, please refer toHow to troubleshoot if the air conditioner fan is running but there is no obvious air supply?。

Aili industrial supporting equipment

Aili Industrial's DC fans and control packages can be evaluated based on the old and new interface tables, and the original electrical diagrams and operating logic can be submitted to help clarify the transformation work and on-site responsibilities. Aili's industrial manufacturing end covers independent R&D and production of motors and fans, control systems, sheet metal, air filters and complete machine assembly. Fan interfaces, control cabinets and original circuits can be matched in the same package; non-standard transformation plans can be adjusted according to the original system circuit and on-site conditions.

Product form can be viewedAir handling unit andFan box page; clean air supply package can be combinedFFU fan filter unit andEFU equipment end fan filter unit verification; multiple equipment linkage can understandMatching method of FFU computer group control system ; terminal particle filtering can be combinedHEPA/ULPA air filter confirmation; when it comes to gaseous pollution control, you can communicate separatelyChemical filter solutions. The specific transformation plan, control interface and delivery scope still need to be verified based on the corresponding configuration data and on-site working conditions. The actual effect is subject to on-site debugging and performance test results.

Submit project parameters:https://ailigy.com/contactus.html

Related questions and answers

If the old control cabinet can start the old motor, can it start the new DC fan directly?
uncertain. The fresh air blower may require different enabling signals, speed control signals or power supply conditions. You should check the interface before making a judgment.

Can the original protection logic still be used after the transformation?
Requires revalidation. The protection provided by the new fan may be different from the protection of the original system. You should confirm that the interlocking and fault handling logic are still valid.

Can Aili Industrial help check the modified interface?
The interface and adaptation plan can be checked based on the original electrical diagram, operating logic and fresh air blower data. Specific modifications need to be confirmed based on site conditions.

Related articles

1. What driving conditions need to be matched when using a DC fan in an air-conditioning box?

2. What point tables need to be provided before the air-conditioning box is connected to the building automation system?

3. How to change the debugging sequence of air conditioning box from stand-alone unit to system linkage?

4. What conditions need to be checked before the air conditioner is turned on for the first time?

Key points for selection and acceptance inspection