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Working Principle and Fault Analysis of Purifying Hot Air Circulation Oven
Feb 27, 2018

Working Principle and Fault Analysis of Purifying Hot Air Circulation Oven

1, purification hot air circulation oven failure analysis and solution

  2.1 Fault Symptom Description

  Open the oven air switch, according to the operating instructions of the oven set the heating

 temperature of 250 ℃, over-temperature alarm temperature of 260 ℃, insulation time 1h, start

 its automatic operation program, the oven cycle fan, fan, dish valve, heating The LEDs light up 

in sequence, indicating that the program is operating normally. Heating operation 2.5h, the 

temperature is still less than the set value, if the heating time is too long, it will be heated 

glass containers fragile, bad bottle rate increased. At the same time, resulting in energy waste,

 increased power consumption. And the working cycle of the oven lengthened, resulting in the

 normal production positions under the two shifts can not be completed on time, the process of

 production process errors, and improve the production costs. Normal full box temperature from

 room temperature has been heated to 250 ℃ need 2.5h, a work cycle needs about 6h.

  2.2 Failure Analysis

  First look at the oven differential pressure table to determine whether the normal wind speed

 inside the oven. Understand the circulation oven is heated items placed too dense, high

 temperature and high efficiency filter is blocked, the air volume adjustment board is changed,

 to exclude these reasons, and then determine whether the circulating fan failure, resulting

 in hot air circulating air circulation is not good, hot and humid air Can not be normal

 discharge. Second, from the fault phenomenon and the oven circuit principle analysis, the 

oven can be heated, indicating a GCD-23A intelligent computer temperature controller output

 signal normal, PLC input and output signals are normal.

  2.3 Fault detection and elimination

  After the above failure analysis, we can conclude that the control signal and adjustable 

components are normal, and then we check from the following aspects. First check the GCD a 23A 

intelligent computer temperature controller PID adjustment parameters to see if the human error

, resulting in set parameter changes, making the system abnormal action. PID parameters directly 

affect the regulation accuracy of the system, which is the core content of the control system

 design. The appropriate PID parameters can be used to calculate the system control quantity

 according to the error characteristics of the process controlled by the system. The corresponding

 output response characteristics can be obtained by using the proportional, integral and 

differential control system to achieve a satisfactory control effect. Restore the PID parameter

 normal setting value. Second, check whether the normal operation of the circulating fan, steering

 is correct. If the fan reversal or fan load is too large and too slow, will affect the hot air 

circulation is not smooth.


When the fan reverses, the fans can be any two-phase power switch; when the fan speed is too slow,

 the two aspects should be checked: (1) the electrical power supply voltage is normal, with or

 without the phenomenon of winding or winding fault. (2) whether the mechanical sweep chamber, 

vibration, bearing overheating, damage, loose leaves and other shell failure shell. Exclusion can

 be made on a case-by-case basis. Again to detect whether the solid-state relay and heater circuit

 breaker. Solid state relay (SOLIDSTATERELAYS), abbreviated as 'SSR', is a kind of all-solid-state

 electronic components of the new non-contact switching devices, which use electronic components 

(such as switching transistors, triacs and other semiconductor devices) switching characteristics,

 (Non-contact switch) .SSR successfully achieved the weak signal (Vsr) on the strong (the output 

load voltage) of the control (the output voltage of the load) to achieve the non-contact without 

sparking the purpose of turning on and off the circuit, .SSR virtual connection or conduction 

after the partial opening of the 380V power supply phase loss, the heater can not be all heated,

 the treatment method is to repair or replace the solid-state relay.Half heater partial circuit,

 but also make the heating can not all work, resulting in heating process After the 2.5h heating,

 the oven reaches the set temperature, the time relay to start the time, the temperature of the

 oven to reach the set temperature, the temperature of the oven is too low, The oven into the 

intermittent heating insulation sterilization stage. Insulation 1h after the oven cooling start 

cooling, 2.3h after the end of the entire drying and sterilization cycle of the program, fully

 meet the oven to provide technical parameters and process parameters.

2, the purification of hot air circulation oven working principle

  Box temperature control using a GCD a 23A intelligent computer temperature control and PLC 

automatic control system, the temperature signal acquisition with platinum resistance,

 the temperature controller amplification and set value to be compared PID control signal,

 while the PLC program control output Control signal control solid-state relay SSR conduction, 

solid-state relay and then control the heater heating, the cabinet in the temperature 

dehumidification stage. When the temperature reaches the set value, the temperature controller

 output PID control signal PLC, PLC output control signal to the time relay KT, to start the

 insulation time, at the same time, close the inlet and exhaust valve. Through the PID control 

electric heating constantly open and close, the box in the hot air circulation sterilization

 sterilization stage. When the heat sterilization time reaches the set value, the time relay 

output signal to the PLC, PLC output fully closed heating, open the water cooling solenoid valve,

 so that suction conduction, which is cooling the cooling stage. When the temperature drop within

 the box ≤ 40 ℃, the temperature controller output control signal to the PLC, PLC output close

 the hot air circulation fan, drying sterilization cycle program ends. TEED a 2001K 

over-temperature alarm temperature controller output signal control PLC to run the entire program,

 platinum resistance PT100 test signal to the alarm temperature controller and over-temperature 

alarm set temperature value for comparison, when the actual temperature is lower than the set value

, the output Control signal to the PLC, PLC program normal operation. When the actual temperature 

value exceeds the set value, the output control signal to the PLC, PLC closed running program.

 So over-temperature alarm settings are generally higher than the working temperature of the set


Add: No. 16, Road 3, Sanjiang Industry Zone, Shengzhou, Zhejiang, China

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Email: boris@benoelectric.com

Contact:Charles Yu     

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