Safety type control circuit of marine cab defrosting device and control method of safety type control circuit
By designing a safety control circuit for marine cab defrosting devices, the problem of forgetting to turn on the equipment after power outages in the prior art is solved, and the safety and automation of the defrosting devices are improved, making it easier to adapt to the dimming needs of indicator lights in different environments.
Patent Information
- Application Number
- CN202411845920.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-16
- Publication Date
- 2025-04-22
AI Technical Summary
The existing marine cab defrosting device has the safety hazard of forgetting to turn on the equipment after power is cut off. The lights of navigation at night affect the driver's sight, and the lack of test light function leads to inaccurate identification of the equipment status, and the fan or electric heating failure cannot be accurately determined during the failure, affecting the maintenance of the defrosting system.
A safety control circuit is designed, including power alarm circuit, temperature control circuit, fan operation circuit, electric heating operation circuit and indicator circuit. Components such as power alarm relay, temperature controller, fan and electric heating contactor are used to realize self-starting of power outage, one-click operation, lamp test function and fault determination, ensuring the safe and automated operation of the defrost system.
It effectively avoids safety hazards caused by forgetting operation by personnel, improves the safety and automation of the defrost device, ensures the normal operation and maintenance of the cab defrost system, and facilitates the dimming needs of the indicator lights in different environments.
Smart Images
Figure CN119861609A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a marine defrosting technology, in particular to a safety control circuit and a control method of a marine cab defrosting device. Background Art
[0002] With the development of ships, the need for defrosting the wheelhouse of ships operating in the global environment has always been a difficult problem that the shipbuilding industry has not yet solved. For example, some ocean-going ships, ro-ro passenger ships, and scientific research ships may cause major safety hazards during navigation due to imperfect control of the defrosting device in the wheelhouse: forgetting to turn on the equipment in time after power failure; bright lights during navigation at night, affecting the driver's vision; no test light function, unable to accurately determine the status of the equipment; in addition, when a fault occurs, it is impossible to be prepared to determine the fan or electric heating fault, affecting the maintenance of the defrosting system. Summary of the invention
[0003] The present invention provides a safety control circuit and a control method for a marine cab defrosting device which can effectively take into account one-key operation and automatic starting when power is off, thereby avoiding hidden dangers caused by personnel forgetting to operate, and has the functions of testing lights and adjusting light brightness, thereby greatly improving the navigation safety of ships.
[0004] The technical solution adopted by the present invention is: a safety control circuit of a marine cab defrosting device, including a control power supply, characterized in that: the control power supply is connected in parallel with a power alarm circuit, a temperature control circuit, a fan operation circuit, an electric heating operation circuit and an indication circuit, the power alarm circuit is connected in series with a power alarm relay, and the normally closed switch of the power alarm relay is connected to the comprehensive alarm circuit; the temperature control circuit is connected in series with a temperature controller, and the temperature controller is connected to a temperature sensor arranged after the fan is electrically heated; the fan operation circuit is connected from one end of the control power supply through the fan thermal relay in sequence to the other end. The ground knob start switch, remote switch, and fan contactor are connected to the other end of the control power supply. The fan contactor is connected in parallel with the fan operation relay. The contact of the fan contactor is connected between the fan power supply and the fan. The fan operation relay normally open switch is connected to the fan operation circuit. The overload contact of the fan thermal relay is connected to the other end of the control power supply through the overload relay; the electric heating operation circuit is connected from one end of the control power supply through the electric heating over-temperature protection normally closed switch through the fan contactor normally open switch, the temperature controller normally open switch, and the electric heating contactor to the other end of the control power supply. The contact of the electric heating contactor is connected to the electric heating power supply and the electric heating The electric heating contactor is connected in parallel with an electric heating relay, the normally open power-off delay switch of the electric heating contactor is connected in parallel with the local knob start switch and the remote switch, the normally open switch of the fan contactor, the normally open switch of the temperature controller and the electric heating contactor are connected in parallel with the over-temperature relay, the over-temperature relay alarm normally closed switch and the overload relay alarm normally open switch are connected in parallel with the power alarm contactor normally open switch, the temperature controller normally open switch is connected in parallel with an electric heating remote switch, and the electric heating remote switch is connected to the remote operation circuit; the indicator circuit is connected to the switch power supply, and the switch power supply output is connected to the potentiometer and then divided into five ways to connect back to the switch Turn off the power, connect the overload relay indicating normally open switch and overload indicator light in series on the first path, connect the over-temperature relay indicating normally closed switch and over-temperature indicator light in series on the second path, connect the fan operation relay indicating normally open switch and fan operation indicator light in series on the third path, connect the electric heating relay indicating normally open switch and electric heating operation indicator light in series on the fourth path, and the fifth path is divided into four paths through the test button and connected in parallel through four diodes to the overload relay indicating normally open switch, over-temperature relay indicating normally open switch, fan operation relay indicating normally open switch and electric heating relay indicating normally open switch on the first, second, third and fourth paths respectively.
[0005] The switching power supply is AC220V / DC24V.
[0006] The control power supply is a transformer power supply.
[0007] The electric heating operation circuit is also provided with a local knob shutdown switch located between the normally open switch of the fan contactor and the normally open switch of the temperature controller.
[0008] A safety control method for a marine cab defrosting device, characterized in that: a. After power-on, when the control power supply is not faulty, the power alarm relay on the power alarm circuit is energized, the normally closed switch of the power alarm relay is opened, and the integrated alarm circuit does not emit sound, light, and signal light integrated alarms; if the control power supply fails, the power alarm relay on the power alarm circuit is not energized, the normally closed switch of the power alarm relay remains closed, and the integrated alarm circuit emits sound, light, and signal light integrated alarms; b. When the defrosting operation is started, the local knob start switch and the remote switch need to be turned on at the same time, the fan operation circuit is connected, the fan contactor and the fan operation relay are energized, the fan contactor contacts are closed to connect the fan power supply and the fan, the fan is started, the fan operation relay normally open switch is closed, and the fan operation circuit displays the fan operation externally; the fan operation relay indication normally open switch is closed, and the fan operation indicator light displays the fan operation; c. Electric heating starts. The temperature controller detects the air supply temperature after the fan is electrically heated through the temperature sensor on the temperature control circuit, thereby controlling the normally open switch of the temperature controller to close. At this time, the fan contactor is energized, the normally open switch of the fan contactor is closed, the electric heating operation circuit is connected, the electric heating contactor and the electric heater relay are energized, and the normally open power-off delay switch of the electric heating contactor is closed to lock the local knob start switch and the remote switch to ensure the continuous operation of the fan; the electric heating relay indicates that the normally open switch is closed, and the electric heating operation indicator shows that the electric heating is running; d. After the electric heating defrosting temperature reaches the set temperature, the temperature controller detects the air supply temperature, the temperature controller normally open switch is disconnected, the electric heating contactor and the electric heating relay lose power, the electric heating is disconnected, and the electric heating contactor normally open power-off delay switch is delayed to open, the fan running circuit is delayed to disconnect, and the fan contactor delays to control the fan to stop; c. To actively shut down, just operate the local knob stop switch; after power failure and shutdown, if the local knob start switch and remote switch remain closed, the startup step of step b will be automatically entered; d. When the air supply temperature after electric heating exceeds the set temperature, the temperature controller fails to control the normally open switch of the temperature controller to be disconnected, and the normally closed switch of the electric heating over-temperature protection is opened, the electric heating operation circuit is disconnected, the electric heating contactor and the electric heating relay lose power, and the electric heating is disconnected. At this time, the normally open power-off delay switch of the electric heating contactor is delayed to open, the fan operation circuit is delayed to be disconnected, and the fan contactor delays to control the fan to stop; at this time, the over-temperature relay alarm loses power, the over-temperature relay alarm normally closed switch is closed, and the comprehensive alarm circuit emits a sound, light and signal light comprehensive alarm; at the same time, the over-temperature relay indication normally closed switch is closed, and the over-temperature alarm indicator light is on to indicate an over-temperature fault alarm; e. When the fan is overloaded, the fan thermal relay is disconnected, the fan contactor and the fan operation relay lose power, the fan stops, the fan operation relay normally open switch opens, and the fan operation circuit shows that the fan is not running; at this time, the overload contact of the fan thermal relay is connected to the overload relay to be energized, the overload relay normally open switch closes, and the comprehensive alarm circuit emits a sound, light and signal light comprehensive alarm; at the same time, the fan operation relay indicator normally open switch closes, and the fan operation indicator lights up to indicate the fan operation fault alarm; f. According to different interference environments and daytime and nighttime environments, adjust the potentiometer to match the voltage of the five-way indicator circuit to ensure the dimming voltage and the dimming accuracy when the overload indicator, over-temperature indicator, fan operation indicator, and electric heating operation indicator are used with diode indicators; g. Measure and control the indicator light brightness. Press the test button to connect the first, second, third and fourth overload indicator lights, over-temperature indicator lights, fan operation indicator lights and electric heating operation indicator lights through diodes. Adjust the potentiometer to control the brightness of each indicator light and test whether the indicator lights are normal.
[0009] The present invention adopts a combination of a power alarm circuit, a temperature control circuit, a fan operation circuit, an electric heating operation circuit and an indication circuit, which can test the status of the indicator light equipment before starting up, monitor the power supply and the temperature after electric heating after starting up, and calculate the temperature setting value according to the heat energy required for defrosting in the cab. The temperature controller controls the automatic start and automatic shutdown of the electric heating after defrosting is required and the fan is started, and can automatically control the start of the defrosting operation after power failure and power on again; combined with temperature control protection, the electric heating and the fan are disconnected for over-temperature protection of the electric heating and over-heating of the fan, and an alarm is indicated, which effectively improves the safety and automation of the defrosting device; and the indicator light is dimmed to adapt to different occasions and environments to avoid the poor anti-interference ability caused by the direct 220V of the diode indicator light, and the potentiometer can adjust the voltage of 24V to light up, and the dimming is more suitable for visual accuracy resolution and safe visibility during navigation. BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Figure 1 This is a circuit diagram of the present invention.
[0011] In the figure: control power supply 1, power alarm circuit 2, temperature control circuit 3, fan operation circuit 4, electric heating operation circuit 5, indication circuit 6, comprehensive alarm circuit 7, fan operation circuit 8, remote operation circuit 9, power alarm relay KA3, power alarm relay normally closed switch KA3-1, temperature controller ST, temperature controller normally open switch ST-1, fan thermal relay FR, local knob start switch SS1, remote switch SS2, electric heating remote switch SS3, local knob stop switch SS4, fan contactor KM2, fan contactor normally open switch KM2-1, overload relay KA1, overload relay alarm normally open switch KA1-1, overload relay indication normally open Off KA1-2, fan operation relay KA2, fan operation relay normally open switch KA2-1, operation relay indication normally open switch KA2-2, electric heating over-temperature protection normally closed switch CW, electric heating contactor KM1, electric heating contactor normally open power-off delay switch KM1-1, electric heating relay KA4, electric heating relay indication normally open switch KA4-1, over-temperature relay KA5, over-temperature relay alarm normally closed switch KA5-1, over-temperature relay indication normally closed switch KA5-2, switching power supply TA, potentiometer R, overload indicator light HL1, over-temperature indicator light HL2, fan operation indicator light HL3, electric heating operation indicator light HL4, test button SB5, diode ZJ. DETAILED DESCRIPTION
[0012] The following is a further description with reference to the accompanying drawings.
[0013] Figure 1 As shown, a safety control circuit of a marine cab defrosting device includes a control power supply 1, to which a power alarm circuit 2, a temperature control circuit 3, a fan operation circuit 4, an electric heating operation circuit 5 and an indication circuit 6 are connected in parallel.
[0014] The power alarm circuit 2 is connected in series with a power alarm relay KA3, and the normally closed switch KA3-1 of the power alarm relay is connected to the integrated alarm circuit 7.
[0015] The temperature control circuit 3 is serially connected to a temperature controller ST, and the temperature controller ST is connected to a temperature sensor arranged after the electric heating of the fan.
[0016] The fan operation circuit 4 is connected from one end of the control power supply 1 through the fan thermal relay FR and in sequence through the local knob start switch SS1, the remote switch SS2, and the fan contactor KM2 to the other end of the control power supply. The fan contactor KM2 is connected in parallel with the fan operation relay KA2, and the contacts of the fan contactor are connected between the fan power supply and the fan. The fan operation relay normally open switch KA2-1 is connected to the fan operation circuit 8, and the overload contact of the fan thermal relay FR is connected to the other end of the control power supply through the overload relay KA1.
[0017] The electric heating operation circuit 4 is connected from one end of the control power supply 1 through the electric heating over-temperature protection normally closed switch CW through the fan contactor normally open switch KM2-1, the local shutdown knob switch SS4, the temperature controller normally open switch ST-1, and the electric heating contactor KM1 to the other end of the control power supply. The contacts of the electric heating contactor are connected between the electric heating power supply and the electric heating. The electric heating contactor KM1 is connected in parallel with the electric heating relay KA4, and the electric heating contactor normally open power-off delay switch KM1-1 is connected in parallel with the local knob start switch and the remote switch. The fan contactor normally open switch, the local shutdown knob switch, the temperature controller normally open switch and the electric heating contactor are connected in parallel with the over-temperature relay KA5. The over-temperature relay alarm normally closed switch KA5-1 and the overload relay alarm normally open switch KA1-1 are both connected in parallel with the power alarm contactor normally open switch KA3-1. The temperature controller normally open switch ST-1 is connected in parallel with the electric heating remote switch SS3, and the electric heating remote switch SS3 is connected to the remote operation circuit 9.
[0018] The indication line 6 is connected to an AC220V / DC24V switching power supply TA, the output of the switching power supply is connected to a potentiometer R and then divided into five paths to connect back to the switching power supply. The first path is connected in series with an overload relay indicating a normally open switch KA1-2 and an overload indicator light HL1, the second path is connected in series with an over-temperature relay indicating a normally closed switch KA5-2 and an over-temperature indicator light HL2, the third path is connected in series with a fan operation relay indicating a normally open switch KA2-2 and a fan operation indicator light HL3, the fourth path is connected in series with an electric heating relay indicating a normally open switch KA4-1 and an electric heating operation indicator light HL4, the fifth path is divided into four paths through a test button SB and respectively connected in parallel to the overload relay indicating a normally open switch, the over-temperature relay indicating a normally open switch, the fan operation relay indicating a normally open switch, and the electric heating relay indicating a normally open switch of the first, second, third, and fourth paths through four diodes ZJ.
[0019] A safety control method for a marine cab defrosting device: a. After power-on, when the control power supply is not faulty, the power alarm relay on the power alarm circuit is energized, the normally closed switch of the power alarm relay is opened, and the integrated alarm circuit does not emit sound, light, and signal light integrated alarms; if the control power supply fails, the power alarm relay on the power alarm circuit is not energized, the normally closed switch of the power alarm relay remains closed, and the integrated alarm circuit emits sound, light, and signal light integrated alarms; b. When the defrosting operation is started, the local knob start switch and the remote switch need to be turned on at the same time, the fan operation circuit is connected, the fan contactor and the fan operation relay are energized, the fan contactor contacts are closed to connect the fan power supply and the fan, the fan is started, the fan operation relay normally open switch is closed, and the fan operation circuit displays the fan operation externally; the fan operation relay indication normally open switch is closed, and the fan operation indicator light displays the fan operation; c. Electric heating starts. The temperature controller detects the air supply temperature after the fan is electrically heated through the temperature sensor on the temperature control circuit, thereby controlling the normally open switch of the temperature controller to close. At this time, the fan contactor is energized, the normally open switch of the fan contactor is closed, the electric heating operation circuit is connected, the electric heating contactor and the electric heater relay are energized, and the normally open power-off delay switch of the electric heating contactor is closed to lock the local knob start switch and the remote switch to ensure the continuous operation of the fan; the electric heating relay indicates that the normally open switch is closed, and the electric heating operation indicator shows that the electric heating is running; d. After the electric heating defrosting temperature reaches the set temperature, the temperature controller detects the air supply temperature, the temperature controller normally open switch is disconnected, the electric heating contactor and the electric heating relay lose power, the electric heating is disconnected, and the electric heating contactor normally open power-off delay switch is delayed to open, the fan running circuit is delayed to disconnect, and the fan contactor delays to control the fan to stop; c. To actively shut down, just operate the local knob stop switch; after power failure and shutdown, if the local knob start switch and remote switch remain closed, the startup step of step b will be automatically entered; d. When the air supply temperature after electric heating exceeds the set temperature, the temperature controller fails to control the normally open switch of the temperature controller to be disconnected, and the normally closed switch of the electric heating over-temperature protection is opened, the electric heating operation circuit is disconnected, the electric heating contactor and the electric heating relay lose power, and the electric heating is disconnected. At this time, the normally open power-off delay switch of the electric heating contactor is delayed to open, the fan operation circuit is delayed to be disconnected, and the fan contactor delays to control the fan to stop; at this time, the over-temperature relay alarm loses power, the over-temperature relay alarm normally closed switch is closed, and the comprehensive alarm circuit emits a sound, light and signal light comprehensive alarm; at the same time, the over-temperature relay indication normally closed switch is closed, and the over-temperature alarm indicator light is on to indicate an over-temperature fault alarm; e. When the fan is overloaded, the fan thermal relay is disconnected, the fan contactor and the fan operation relay lose power, the fan stops, the fan operation relay normally open switch opens, and the fan operation circuit shows that the fan is not running; at this time, the overload contact of the fan thermal relay is connected to the overload relay to be energized, the overload relay normally open switch closes, and the comprehensive alarm circuit emits a sound, light and signal light comprehensive alarm; at the same time, the fan operation relay indicator normally open switch closes, and the fan operation indicator lights up to indicate the fan operation fault alarm; f. According to different interference environments and daytime and nighttime environments, adjust the potentiometer to match the voltage of the five-way indicator circuit to ensure the dimming voltage and the dimming accuracy when the overload indicator, over-temperature indicator, fan operation indicator, and electric heating operation indicator are used with diode indicators; g. Measure and control the indicator light brightness. Press the test button to connect the first, second, third and fourth overload indicator lights, over-temperature indicator lights, fan operation indicator lights and electric heating operation indicator lights through diodes. Adjust the potentiometer to control the brightness of each indicator light and test whether the indicator lights are normal.
[0020] The present invention adopts a combination of a power alarm circuit, a temperature control circuit, a fan operation circuit, an electric heating operation circuit and an indication circuit, which can test the status of the indicator light equipment before starting up, monitor the power supply and the temperature after electric heating after starting up, and calculate the temperature setting value according to the heat energy required for defrosting in the cab. The temperature controller controls the automatic start and automatic shutdown of the electric heating after defrosting is required and the fan is started, and can automatically control the start of the defrosting operation after power failure and power on again; combined with temperature control protection, the electric heating and the fan are disconnected for over-temperature protection of the electric heating and over-heating of the fan, and an alarm is indicated, which effectively improves the safety and automation of the defrosting device; and the indicator light is dimmed to adapt to different occasions and environments to avoid the poor anti-interference ability caused by the direct 220V of the diode indicator light, and the potentiometer can adjust the voltage of 24V to light up, and the dimming is more suitable for visual accuracy resolution and safe visibility during navigation.
[0021] In this embodiment, the control power supply is a transformer power supply.
[0022] In this embodiment, the electric heating remote switch SS3 can control the remote manual start of electric heating through the remote operation circuit 9.
Claims
1. A safety control circuit for a marine cab defrosting device, comprising a control power supply, characterized in that: The control power supply is connected in parallel with a power alarm circuit, a temperature control circuit, a fan operation circuit, an electric heating operation circuit and an indication circuit. The power alarm circuit is connected in series with a power alarm relay, and the normally closed switch of the power alarm relay is connected to the comprehensive alarm circuit. The temperature control circuit is connected in series with a temperature controller, and the temperature controller is connected to a temperature sensor arranged after the electric heating of the fan; the fan operation circuit is connected from one end of the control power supply through the fan thermal relay in turn through the local knob start switch, the remote switch, and the fan contactor to the other end of the control power supply, and the fan contactor is connected in parallel with the fan operation relay, and the contact of the fan contactor is connected between the fan power supply and the fan, and the fan operation relay normally open switch is connected to the fan operation circuit, and the overload contact of the fan thermal relay is connected to the other end of the control power supply through the overload relay; the electric heating operation circuit is connected from one end of the control power supply through the electric heating over-temperature protection normally closed switch through the fan contactor normally open switch, the temperature controller normally open switch, and the electric heating contactor to the other end of the control power supply, and the contact of the electric heating contactor is connected between the electric heating power supply and the electric heating, and the electric heating contactor is connected in parallel with the electric heating relay, and the electric heating contactor normally open power-off delay switch is connected in parallel with the local knob start switch and the remote switch, and the fan contactor normally open switch, temperature controller normally open switch, and electric heating contactor are connected to the other end of the control power supply, and the contact of the electric heating contactor is connected between the electric heating power supply and the electric heating, and the electric heating contactor is connected in parallel with the electric heating relay, and the electric heating contactor normally open power-off delay switch is connected in parallel with the local knob start switch and the remote switch, and the fan contactor normally open switch, temperature controller normally open switch, and electric heating contactor are connected to the other end of the control power supply, and the contact of the electric heating contactor is connected between the electric heating power supply and the electric heating, and the electric heating relay is connected in parallel with the electric heating contactor. The controller normally open switch and the electric heating contactor are connected in parallel with an over-temperature relay, the over-temperature relay alarm normally closed switch and the overload relay alarm normally open switch are both connected in parallel with the power alarm contactor normally open switch, the temperature controller normally open switch is connected in parallel with an electric heating remote switch, and the electric heating remote switch is connected to the remote operation circuit; the indication circuit is connected to the switching power supply, and the switching power supply output is connected to the potentiometer and then divided into five paths to connect back to the switching power supply, the first path is connected in series with the overload relay indication normally open switch and the overload indicator light, the second path is connected in series with the over-temperature relay indication normally closed switch and the over-temperature indicator light, the third path is connected in series with the fan operation relay indication normally open switch and the fan operation indicator light, the fourth path is connected in series with the electric heating relay indication normally open switch and the electric heating operation indicator light, and the fifth path is divided into four paths through a test button and respectively connected in parallel with the overload relay indication normally open switch, the over-temperature relay indication normally open switch, the fan operation relay indication normally open switch, and the electric heating relay indication normally open switch of the first, second, third, and fourth paths through four diodes.
2. The safety control circuit of a marine cab defrosting device according to claim 1, characterized in that: The switching power supply is AC220V / DC24V.
3. The safety control circuit of the marine cab defrosting device according to claim 1 is characterized in that: The control power supply is a transformer power supply.
4. The safety control circuit of the marine cab defrosting device according to claim 1 is characterized in that: The electric heating operation circuit is also provided with a local knob shutdown switch located between the normally open switch of the fan contactor and the normally open switch of the temperature controller.
5. A safety control method for a marine cab defrosting device according to claim 1, 2 or 3, characterized in that: a. After power-on, when the control power supply is not faulty, the power alarm relay on the power alarm circuit is energized, the normally closed switch of the power alarm relay is opened, and the integrated alarm circuit does not emit sound, light, and signal light integrated alarms; if the control power supply fails, the power alarm relay on the power alarm circuit is not energized, the normally closed switch of the power alarm relay remains closed, and the integrated alarm circuit emits sound, light, and signal light integrated alarms; b. When the defrosting operation is started, the local knob start switch and the remote switch need to be turned on at the same time, the fan operation circuit is connected, the fan contactor and the fan operation relay are energized, the fan contactor contacts are closed to connect the fan power supply and the fan, the fan is started, the fan operation relay normally open switch is closed, and the fan operation circuit displays the fan operation externally; the fan operation relay indication normally open switch is closed, and the fan operation indicator light displays the fan operation; c. Electric heating starts. The temperature controller detects the air supply temperature after the fan is electrically heated through the temperature sensor on the temperature control circuit, thereby controlling the normally open switch of the temperature controller to close. At this time, the fan contactor is energized, the normally open switch of the fan contactor is closed, the electric heating operation circuit is connected, the electric heating contactor and the electric heater relay are energized, and the normally open power-off delay switch of the electric heating contactor is closed to lock the local knob start switch and the remote switch to ensure the continuous operation of the fan; the electric heating relay indicates that the normally open switch is closed, and the electric heating operation indicator shows that the electric heating is running; d. After the electric heating defrosting temperature reaches the set temperature, the temperature controller detects the air supply temperature, the temperature controller normally open switch is disconnected, the electric heating contactor and the electric heating relay lose power, the electric heating is disconnected, and the electric heating contactor normally open power-off delay switch is delayed to open, the fan running circuit is delayed to disconnect, and the fan contactor delays to control the fan to stop; c. To actively shut down, just operate the local knob stop switch; after power failure and shutdown, if the local knob start switch and remote switch remain closed, the startup step of step b will be automatically entered; d. When the air supply temperature after electric heating exceeds the set temperature, the temperature controller fails to control the normally open switch of the temperature controller to be disconnected, and the normally closed switch of the electric heating over-temperature protection is opened, the electric heating operation circuit is disconnected, the electric heating contactor and the electric heating relay lose power, and the electric heating is disconnected. At this time, the normally open power-off delay switch of the electric heating contactor is delayed to open, the fan operation circuit is delayed to be disconnected, and the fan contactor delays to control the fan to stop; at this time, the over-temperature relay alarm loses power, the over-temperature relay alarm normally closed switch is closed, and the comprehensive alarm circuit emits a sound, light and signal light comprehensive alarm; at the same time, the over-temperature relay indication normally closed switch is closed, and the over-temperature alarm indicator light is on to indicate an over-temperature fault alarm; e. When the fan is overloaded, the fan thermal relay is disconnected, the fan contactor and the fan operation relay lose power, the fan stops, the fan operation relay normally open switch opens, and the fan operation circuit shows that the fan is not running; at this time, the overload contact of the fan thermal relay is connected to the overload relay to be energized, the overload relay normally open switch closes, and the comprehensive alarm circuit emits a sound, light and signal light comprehensive alarm; at the same time, the fan operation relay indicator normally open switch closes, and the fan operation indicator lights up to indicate the fan operation fault alarm; f. According to different interference environments and daytime and nighttime environments, adjust the potentiometer to match the voltage of the five-way indicator circuit to ensure the dimming voltage and the dimming accuracy when the overload indicator, over-temperature indicator, fan operation indicator, and electric heating operation indicator are used with diode indicators; g. Measure and control the indicator light brightness. Press the test button to connect the first, second, third and fourth overload indicator lights, over-temperature indicator lights, fan operation indicator lights and electric heating operation indicator lights through diodes. Adjust the potentiometer to control the brightness of each indicator light and test whether the indicator lights are normal.