Measures to prevent fires caused by electric heaters during operation

Measures to prevent fires caused by electric heaters during operation

1, Flammable and explosive materials should not be placed near electric heaters, and it is necessary to maintain a certain safe distance.

2, It is necessary to place the electric heater on a non conductive and non combustible data base.

3, The safe cut-off flow rate of electric heating wires must meet the capacity requirements of electric heaters, and industrial electric heaters must be equipped with separate circuits in any case.

4, It is necessary to plug the wires of the electric heater, and the wire end of the electric heater should not be directly inserted into the socket. Aging or damaged circuits should be replaced in a timely manner.

5, Put the damaged container into the equipment, and it is necessary for someone to take care of it during use. When disconnecting, unplug the plug. In case of power outage, unplug the electric heater in a timely manner and don't forget.

6, Resistance wires that have been repaired multiple times should not be reused and should be replaced with new ones. Stop using electric heaters to dry various flammable and explosive materials.

7, The temperature setting of the electric heater should not only avoid excessive temperature, but also avoid prolonged baking time of the electric heater.

A method for suppressing peripheral equipment disturbance in air electric heaters

(1) Maintenance of input and output terminals of PLC

To prevent the high induced electromotive force that occurs when the inductive input or output circuit is disconnected from the PLC from having a significant impact, and when the driving components of the PLC are mainly composed of solenoid valves and communication contactor coils, using a zero crossing solid-state relay in the center between the driving components and the PLC output terminal is an effective solution.

(2) Error prevention of input and output signals

To reduce the input current of PLC and the current on external loads, parallel bypass resistors are generally adopted at the input and output terminals.

(3) Leakage current

When selecting DC two wire sensors such as proximity switches and photoelectric switches for input signals, if the leakage current is large, the resulting misoperation should be considered to prevent the PLC input signal from being turned off. At this point, it is possible to connect a bypass resistor to the PLC input terminal to reduce the input impedance. When using bidirectional thyristor as the output, to prevent leakage current and other reasons from causing the output components to fail to turn off, a side resistor can also be connected in parallel at the output end.

(4) Surge voltage

When the controller outputs as a contact, regardless of whether the controller itself can resist disturbances, RC absorption is adopted for communication loads, and freewheeling diodes are used for DC loads to absorb surge voltages generated by inductive loads.

(5) Impulse current

When using transistors or bidirectional thyristor output modules to drive incandescent lamps or other loads with large power sources, it is necessary to connect the PLC output terminal in parallel with a bypass resistor or connect the load in series to limit the current of the resistor to maintain the output module.

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