The temperature switch controls the start and stop of the fan

When the temperature exceeds 36 degrees, the temperature switch closes and sends a signal; when the temperature is below 36 degrees, the switch opens. Sometimes the temperature switch itself has a dead zone, meaning it will only open when the temperature is below 35.5 degrees. The interlock of the fan is implemented within the control system, and it has nothing to do with the temperature switch itself.

When the temperature exceeds 36 degrees, it sends a signal to the control system rather than to the fan control circuit; this signal needs to be logically configured within the fan control circuit (for example, the fan start signal is configured using an RS flip-flop, with the output connected to terminal S)； Signals with a temperature below 30 degrees are connected to terminal R)

Yes, the process you described is correct. The basic principle behind using a temperature switch to control a fan is that when the ambient temperature exceeds 36 degrees, the temperature switch closes and the fan starts operating ； When the temperature drops below 30 degrees, the temperature switch disconnects and the fan stops. During this process, the temperature may continue to rise for a short period before gradually falling, but as long as the temperature remains above 30 degrees, the fan will keep running. When the temperature rises back above 36 degrees, if the fan has stopped, the temperature switch closes again and the fan starts up once more. This allows the ambient temperature to be adjusted effectively by controlling the start and stop of the fan. .

I am a temperature switch that sends signals to the motor’s secondary circuit via an intermediate relay; no controller is required

The start and stop of the temperature-controlled fan is planned to be controlled using a relay

Well, using an intermediate relay to receive the signal from the temperature switch and control the motor is a common method. The specific steps are as follows: 1. When the temperature switch detects that the ambient temperature exceeds 36 degrees, it closes and sends an electrical signal to the intermediate relay. 2. After receiving the signal, the relay closes its contacts, thereby supplying power to the motor’s secondary circuit and starting the fan to operate. 3. When the ambient temperature drops below 30 degrees, the temperature switch turns off, and no signal is sent to the relay. 4. The relay contacts then open, cutting off the power supply to the motor, and the fan stops operating. Such a configuration does not require an additional controller; automatic control of the fan can be achieved using a temperature switch and a relay, which is simple and effective. .

This post was last edited by hanhaigang128 on 2024-12-4 at 20:01. The electrical control cabinets or PLC control cabinets we use are equipped with a temperature control switch. This switch allows for setting a specific temperature at which the fan inside the cabinet is turned on or off. The 220VAC live wire of the fan is connected to one end of the normally open contacts of the temperature control switch, while the common terminal is connected to a 220VAC power supply. When the temperature inside the cabinet exceeds the set value, the normally open contacts close, allowing 220VAC to flow through and starting the fan, which then draws air out of the cabinet to facilitate air circulation and cooling. When the temperature drops below the set value, the normally open contacts switch from closed to open, and the fan stops operating. Of course, using a relay for isolation is a better approach.

When the temperature is above 30 degrees and reaches 36 degrees, switch 1 closes; through self-locking via the relay, the fan starts up and the temperature begins to drop； When the temperature is above 30 degrees and below 36 degrees, switch 1 turns off; due to self-locking, the fan continues to run as the temperature drops further ； When the temperature is below 30 degrees, switch 2 opens, cutting off the power to the relay coil and causing the fan to stop. This is a switch control with a dead zone of 30–36 degrees.

This switch you have is different from the one I’m familiar with. The temperature switch I know closes when the temperature reaches a high set point, and it remains closed until the ambient temperature drops below that value; the low-temperature set point is another value, and there should be a certain difference between the high and low set points, otherwise the motor will start frequently