Soft Starter Inspection and Testing
Improper Soft Starter usage (installation and/or operation) and lack of maintenance (including failure to adjust based on changes in operating conditions) could shorten the service life of a Soft Starter and/or cause Soft Starter failure or faults. The impact of temperature, humidity, dust, and vibration could lead to poor heat dissipation and component aging of Soft Starters (resulting in potential failure or reducing the service life of the Soft Starter). This makes general inspections particularly important (it is recommended that periodic inspections should be conducted at least once a year). Also ensure the correct size Soft Starter is selected for the operation/application – please details HERE.
Before inspecting a Soft Starter, ensure the power supply is cut off (ensure the power indicator of the Soft Starter is off and test the input and output terminals for power).
GENERAL INSPECTIONS
Take note of the Temperature and Humidity of the surrounding environment. Please see details regarding Soft Starter Derating due to Temperature/Altitude/Humidity HERE. Excessive temperatures could cause the Soft Starter to overheat (typically cause an Error alarm). In severe cases, it could damage the Soft Starter’s power components and even cause a short circuit. Inspect for any possible moisture or dirt/dust evident inside the Soft Starter, especially on the circuitry (which could cause short circuits). Excessive humidity could also cause a short circuit inside the Soft Starter.
Check that all components are clean and for any signs of corrosion. If it’s evident that there is a lot of dust or moist inside the Soft Starter itself, open the Soft Starter and clean it.
Inspect all connections and ensure there aren’t any loose screws, bolts, or plug-in’s, also ensure that none of the conductors or insulators are corroded (if necessary, clean by wiping them off with alcohol). Also check for any signs of arcing on any of the component terminals. Ensure that all wiring and contactors/breakers are according to specification – please details HERE.
Also ensure that Shielded/Screened cable (cable with a common conductive outer layer for electromagnetic shielding) is used when connecting a Soft Starter with any external instrumentation (such as PLC’s, etc.).
When the Soft Starter is running, listen for any abnormal sounds or vibrations from the Soft Starter and Motor. Also check the electric motor for possible issues.
Soft Starters (with IP20 rating) are generally installed in cabinets/enclosures/panels, which should also include adequate ventilation and cooling for the Soft Starter. Please see Soft Starter Cooling/Panel Fan Selection details HERE. Also ensure these fans operate smoothly (ensure there are adequate air flow and listen for any abnormal sounds). Ensure that the fans rotate smoothly, rotates in the correct direction (extraction fans should extract hot air out of the enclosure and not suck air in) and that there are no dust or obstructions in the air inlets. Clean the ventilation ducts and fans if necessary and remove any dust deposits that might be present (also remove dust from filters).
BASIC TROUBLESHOOTING
Static Tests (Dry Tests)
- Power Source Voltage: Use a Multimeter to test the Voltage between the different phases of the Power Supply (Not connected to Soft Starter) to ensure the Power Supply is as expected).
- Thyristor Main Circuit: Use a Multimeter to test Conductance (continuity) between Soft Starter Terminals R + U, S + V and T + W. If conducted (Multimeter Beep Test), the Thyristor is Damaged.
- Thyristor Control Circuit: Use a Multimeter to test Resistance between Red + Black Wire and between White + Yellow Wire – should be almost the same, if not, Thyristor is damaged (test for all 3 Thyristors).
Dynamic Tests (Wet Tests)
If the Static Test results are normal, the Dynamic Tests can be performed (power-on tests).
Before Powering On
Check whether the connection ports of the Soft Starter are correctly connected and whether any of the connections are loose (abnormal connections may sometimes cause the Soft Starter to malfunction).
After Powering On
- Power Supply Voltage: Use Multimeter to test the Voltage between the different phases of each of the Soft Starter Terminals (R, S and T) with the power supply connected (and switched on) to the Soft Starter (to ensure power supply is as expected). Also check the Supply Voltage as displayed on the Soft Starter Operating Panel (Keypad) – when the Soft Starter is powered on and showing a READY STATE on the screen, press the YES button, scroll through the options using the Up and Down arrow buttons on the Keypad until the Voltage is displayed.
- Control Board Power and Keypad: If the supply voltage is normal and the Keypad does not work (no display), it could be caused by a faulty Cable Socket (on Keypad itself or on Control Board) or damaged Keypad or Cable. Firstly, remove the Keypad and check whether the LED indicator on the Control Board is on after the Soft Starter is powered on. If the LED Indicator does not go on, the Control Board are most likely damaged, please contact us for support. If the LED indicator goes on, it means the Control Board is OK and the problem could be between the Control Board and Keypad connection (cable or sockets). To test (first switch off all power supply), disconnect and connect the cable between the Control Board and Keypad to ensure they are connected properly. If the issue persists (after power on again), replace the Keypad to confirm whether it’s a faulty Keypad and replace the Cable to confirm whether it’s a faulty Cable. If it’s not a Cable or Keypad issue, also test the DC Voltage on the Control Board between the Public (10) Terminal and each of the Start/Stop (7, 8, and 9) Terminals to confirm a ~12V reading is obtained – if not, please contact us for support (could be damaged Control Board).
- Errors: If the Operating Panel (Keypad) displays a fault (Error Code) after powering on, please look up the Fault Code from the Fault Codes and Descriptionsin the manual (listing possible reasons/causes and solutions). For additional Fault Information it’s also very helpful to review the Error Log (last 9 errors and descriptions of the faults). To view the Error Log, please see the FAQ Entry Here (when contacting us for support it might be easier to simply take a video of the error log by entering through all the parameters and sending us the video).
- Parameter Settings: Check whether the Motor Rated Current are set correctly (Parameter FP) and whether any other abnormal parameter settings can be identified – if so, doing a factory reset could be a good idea (please see FAQ Entry Here as guideline on how to do a Factory Restore).
- Phase Voltage (Not Running): With the Power Source On and Soft Starter in STOP mode, use a Multimeter to test the Voltage between the different phases of each of the Soft Starter Terminals R + U, S + V and T + W. Phase to Phase Voltage will measure the same as Input Voltage if No Load is connected, if a load is connected (Not Running), the Voltage will be low (~3V) – measurements due to characteristics of the thyristors.
- Transformer Voltage: To test this the Keypad and Control Board needs to be removed and the Transformer unplugged – please remove all power before removing all this and make sure it’s safe to switch the power back on to test the transformer (this test should be done by skilled technicians only). The Transformer has 6 small cables: two Yellow, two Blue and two Green Measure the Voltage between each pair. Yellow should be ~ 18-20Vac, Blue and Green should be ~ 9Vac.
Start the Soft Starter (Running Load Test)
Next, start the Soft Starter with a load connected (when testing, it is best to test at full load). If the motor starts up and is running, check whether the Current displayed on the Keypad is accurate (as expected), similarly, also check the Output Voltage as displayed on the Keypad. After this, also test whether the Output Voltage and Current are balanced on the U, V and W output terminals and corresponds with the readings as displayed on the Keypad. If there is a phase loss, phase unbalance, or large variance between Keypad display values and actual measured values, please contact us for support.
If none of the above steps helped identify and/or resolve the issue, please contact us for support.
Contacting us for Support
Please note, when contacting us for support, please try and provide as much information as possible, such as:
- Photo of the Soft Starter Nameplate.
- Photo of the Motor Nameplate.
- Photo’s/Video’s showing the installation and setup.
- Details regarding the specific application and configuration/setup used.
- Details regarding the undesired/unexpected behaviour/observations (ideally with photo/video evidence showing the occurrence).
- Error Log information as obtained from the Soft Starter – please see the FAQ Entry showing how to access the Error Log Here (it might be easier to simply take a video of the error log values by entering through all the parameters and sending us the video).
