GE Industrial Solutions AF-600 FP High Power Unit Sizes 6x - Manual (Page 46)

4 Troubleshooting
4.1 Troubleshooting Tips
Before attempting to repair a frequency converter, here are some tips to follow to make the job easier and possibly prevent unnecessary damage to functional
components.
1. Ensure that no voltage is present on the frequency converter prior to troubleshooting. Check for the presence of AC input voltage and DC bus voltage
and ensure there is none before working on the unit. Remember that voltage may be present for as long as 40 minutes after removing power from
the unit. See the label on the front of the frequency converter door for the specific discharge time. Some points in the frequency converter are
referenced to the negative DC bus and are at bus potential even though it may appear on diagrams to be a neutral reference.
2. If any of the DC bus fuses are blown, always ensure no DC bus voltage is present on either side of the DC fuses. When any DC bus fuse is blown, capacitor
banks in the other inverter modules are no longer electrically connected. As a result, one inverter module may have stored voltage even when the rest
of the unit has none.
3. Darkened LED lights on the Keypad does not mean that the drive has no dangerous internal voltage. Do not assume the unit contains no voltage when
the indicator lights are off.
4. Never apply power to a unit that is suspected of being faulty. Many faulty components within the frequency converter can cause damage to other
components when power is applied. Always perform the procedure for testing the unit after repair as described in Section Test Procedures.
5. With an external power supply and cable assembly, the logic section of the frequency converter can be powered without applying power to the rest of
the unit. This method of power isolation is recommended for troubleshooting logic problems.
6. Never attempt to defeat any fault protection circuitry within the frequency converter. That will result in unnecessary component damage and may cause
personal injury.
7. Always use factory approved replacement parts. The frequency converter has been designed to operate within certain specifications. Incorrect parts
may affect tolerances and result in further damage to the unit.
8. Read the instruction and service manuals. A thorough understanding of the unit is the best approach. If ever in doubt, consult the factory or authorized
repair centre for assistance.
4.2 Exterior Fault Troubleshooting
There may be slight differences in servicing a frequency converter that has been operational for some extended period of time compared to a new installation.
When using proper troubleshooting procedures, make no assumptions. To assume a motor is wired properly because the frequency converter has been in service
for some time may cause you to overlook loose connections, improper programming, or added equipment, for example. It is best to develop a detailed approach,
beginning with a physical inspection of the system. See Table Visual Inspection for items to examine.
4.3 Fault Symptom Troubleshooting
This troubleshooting section is divided into sections based on the symptom being experienced. To start the following table provides a visual inspection check list.
Many times the root cause of the problem may be due to the way the frequency converter has been installed or wired. The check list provides guidance through
a variety of items to inspect during any frequency converter service process.
Next, symptoms are approached as the technician most commonly discovers them: reading an unrecognised frequency converter display, problems with motor
operation, or a warning or alarm displayed by the frequency converter. Remember, the frequency converter processor monitors inputs and outputs as well as
internal frequency converter functions, so an alarm or warning does not necessary indicate a problem within the frequency converter itself.
Each incident has further descriptions on how to troubleshoot that particular symptom. When necessary, further referrals are made to other parts of the manual
for additional procedures. The section Frequency Converter and Motor Applications presents detailed discussions on areas of frequency converter and system
troubleshooting that an experienced repair technician should understand in order to make effective diagnoses.
Finally, a list of tests called After Repair Tests is provided. These tests should always be performed when first starting a frequency converter, when approaching
a frequency converter that is suspected of being faulty, or anytime following a repair to the frequency converter.
High Power Service Manual for Unit Sizes 6x
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