- CHECK STATUS OF POWER STAGE
Variable speed AC motor in general have the power terminal block as shown in Figure 3-13.
The first terminal (GND) starting from the left is the "land" of the input line. The terminals labeled L1 (R), L2 (S) and L3 (T) are those who receive VAC power supply installation. + DB terminal is optional and serves to place an external resistor (provided by the manufacturer) that enables the dynamic braking mode (Dynamic Brake: DB) engine. The terminals U, V, W are the inverter phase output, which must connect to the AC induction motor control. And finally, the GND terminal on the far right must be connected to engine ground. The DC terminal is usually located in close proximity to the terminal.
For testing the power stage, drive the team must be fully disconnected from the VAC for a period of at least 3 minutes to allow the discharge of the capacitor bank.
After the power terminals located with the help of Figure 3-8 and a digital voltmeter, proceed to test the LEDs on the rectifier stage. We recommend using the meter scale diodes. The terminals involved in that test are: L1, L2, L3, + DB and-DB. Check the result according to Table 3-2.
Note that the other possible combinations of measurement should result in the maximum scale "OL" the meter.
To test the Investor borneras just choose the U, V, W, + DB and-DB, where we will find reading diodes (damper diodes for protection), measured as the maximum scale IGBTs.
Refer to Table 3-3 to check the result of its size.
The other possible measure combinations should result in the maximum scale "OL" the meter.
The test capacitor bank is made with the ohm meter scale noting that the value should be increased ohms from a minimum to open finally.
Some manufacturers give such information, the lifetime of the capacitors. Such as the drive manufacturer Brand: MITSUBISHI, reports that its capacitor banks should be replaced after 5 years of continuous use.
It is advisable to read the manufacturer's manual to know how many years of life gives the capacitor bank prior to its replacement.
If the results of all measurements are satisfactory, ie reading the diodes 12 are in the rectifier and inverter, proceed to the next step.
- CHECK STATUS OF CONTROL STAGE
To proceed to testing the control stage, you must have read and understood the information provided by the manufacturer.
Variable speed AC motor with a programming panel also serves to display the parameter to adjust.
Figure 3-14 shows the example of the programming panel provided by the manufacturer for your drive model SIEMENS: MICROMASTER VECTOR
The layout of each of the terminals for the control stage is shown in Figure 3-14.
(Click on the image to enlarge)
In the previous figure we see that the terminal is a control terminal strip 26, of which the manufacturer gives us indications of the steps for testing operation.
As an example for the case of the MICROMASTER, the manufacturer says that for initial testing must:
1 .- Check that all cables are connected correctly and whether they have met all the safety precautions relating to equipment.
2 .- Apply mains to the inverter.
3 .- Ensure that the engine start can be performed safely. Press the START of the drive. The display will change to 5.0 Hz and the spindle motor begins to rotate. The acceleration time to 5 Hz will be 1 second. Obviously these values of parameters have been programmed at the factory ("defaults") and we can change them after ascertaining that the equipment is operational and well adapted to our requirements.
4 .- Check that the motor rotates in the right direction. Press the sense DIRECT / REVERSE if necessary.
5 .- Press the STOP button. The display will change to 0.0 and the engine began to slow to a complete stop in 1 second.
As we can see is very important to have on hand the respective manuals.
