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Maintenance and inspection procedures for frequency converters and soft starters

Sep 27, 2020

Maintenance and inspection procedures for frequency converters and soft starters


 Maintenance and inspection are effective means to prevent accidental failure of the device. In order to effectively perform maintenance and inspections, an inspection sheet should be prepared to record and save the inherent characteristic changes of the device and the stability of its constituent parts to prevent malfunctions and investigate the causes of malfunctions when they occur. Maintenance and inspection are divided into daily inspections and regular inspections. At the beginning of the installation of the device, the inspection cycle should be shortened and the inspection should be carried out in detail to prevent initial failures. After the operation time becomes longer, it is necessary to check whether the components have degraded characteristics.

 1. Preparation steps for inspection and maintenance

 Stop device → main circuit power supply OFF → control power supply OFF → confirm main circuit power supply discharge → electrical inspection

 2. Daily inspection

2.1 Inspection cycle: once a month.

2.2 Inspection items:

 ①Confirm the installation environment: confirm the temperature, humidity, presence or absence of special gas, and presence or absence of dust;

 ②Confirm whether the reactor, transformer, cooling fan, etc. have abnormal sounds and vibrations;

 ③Confirm whether there is any peculiar smell, the smell of insulators and the unique smell of each circuit component;

 ④Confirm the dirt inside the equipment, and reduce the cleaning cycle according to the dirt;

For the above items, visual inspection shall be the center of implementation, and repairs should be carried out immediately if there are abnormalities.

 3. Regular inspection

3.1 Inspection cycle: According to the minor repair cycle of the unit.

 3.2 The items to be checked are as follows:

 ①Cleaning inside the cabinet;

 ②Cleaning inside the equipment;

 ③ Confirmation of discoloration, deformation and leakage of circuit components (capacitors, resistors, reactors, transformers, etc.);

      ④Confirmation and cleaning of substrate (discoloration and deformation of resistance and capacitor, discoloration, deformation, dirt of substrate, aging of welding, etc.);

 ⑤ Confirmation of wiring (whether there is discoloration or corrosion due to heat);

 ⑥ Confirmation of fastening parts (looseness of bolts, nuts, screws);

 When inspecting the main circuit part of the device, after disconnecting the input power supply, after about 5 minutes have passed, the inspection should be performed.

 Please note: the capacitor inside the device will remain charged for a period of time after the input power is disconnected, and there is a danger of electric shock.

 In addition, in order to prevent electric shock accidents, do not open the door while the equipment is operating.

 4. Maintenance focus

 1. Clean the main circuit and control circuit

 The first step in maintenance and inspection is cleaning. Cleaning should be implemented according to the condition of the equipment. When cleaning, cut off the power and confirm that the main circuit has no voltage, and then remove the dust from the equipment by suction or blowing. Note: If the pressure of compressed air is too strong, it may damage components and wiring. In addition, attachments that cannot be removed by blowing should be wiped off with a cloth. In principle, cleaning starts at the top and ends at the bottom. Dust and metal chips fall from the top. If you check from the bottom first, you can't find and remove the falling objects.

 2. Cabinets and structural supplies

 (1) Cooling fan (anytime)

 Check whether the air volume is abnormal and whether the fan noise has increased. Especially when reinstalling after removal, if you forget to tighten the bolts, etc., the bearing blades etc. will be damaged due to vibration, so be careful.

 (2) Main circuit components, the entire cabinet (1 time/month to 1 time/year)

 Check whether there is dust accumulation in the case, the reactor, the conductor fastening part, the fuse, the capacitor, and the resistor for discoloration, heat generation, abnormal sound, odor, or damage.

 Check carefully whether the wiring and installation parts are broken, disconnected wiring, tightening is not loose, and whether there is any damage.

 3. Printed circuit board

 Printed circuit boards composed of integrated circuits and electronic components need to be protected from dust, corrosive gases, temperature, etc. Therefore, the installation environment of the equipment should be considered. In addition, regular inspections and cleanliness and maintaining a good environment are also very important to reduce failures.

 Because the parts are small and the ability to withstand external forces is poor, so when cleaning, you should use a brush to wipe.

3.1 Precautions for use

 3.1.1 The maintenance of the printed circuit board must be performed after 5 minutes after cutting off all power.

 3.1.2 When removing the printed circuit board, all connectors and wires should be removed, and the fixing screws on the upper part of the printed circuit board should be removed.

 3.1.3 At this time, be careful not to drop the printed circuit board and fixing screws.

 3.1.4 When installing a printed circuit board, follow the reverse steps when removing it.・

 3.1.5 In addition, because the control circuit board has a capacitor, even if the power is cut off, the

Some parts are working. Keep the aluminum frame down, and be careful not to short-circuit.

 5. Device inspection and maintenance procedures

1. Preparation steps:

    Stop the device and confirm that the motor has stopped completely.

    Press the stop button on the operation panel to disable operation.

   Disconnect the external main power supply (low-voltage cabinet drawer). Adequate safety treatment should be carried out to ensure that it is disconnected and that there will be no misuse.

   Check to make sure that the power indicator on the control panel and inverter (soft starter) panel is off.

    Disconnect the control power air switch (fuse).

    Wait for more than 5 minutes.

    Open the door lock of the inverter (soft starter) cabinet and open the cabinet door.

    Check the power at the main circuit input terminal to ensure that the main circuit voltage is at a safe level.

    When opening the door of the inverter (soft starter) unit cabinet, confirm that the LED lights of all the unit inverters (soft starters) are turned off.

 Check that there is no voltage at the external cable terminal used to connect to the control cabinet.

 Check the control power input terminal to ensure that the control power voltage is at a safe level.

 Ground the three-phase input power at the input end of the main circuit.

 Start inspection and maintenance.

 (14) In the case of replacing the unit inverter (soft starter), please follow the instruction manual inverter (soft starter) instruction manual.

 2. Recovery steps:

1. Remove the ground wire of the main circuit.

2. Turn on the control power and close the door. If the control power supply is not turned on, it cannot operate.

3. Power on the external main power supply (low-voltage cabinet drawer). When the external main power supply is turned on, it must be confirmed that the indicator light on the control panel is on.

 4. Carry out safety confirmation and prepare for operation.