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Troubleshooting Backup Power

System Troubleshooting

Electronic Troubleshooting Capabilities
Emergency or backup power generation for a facility includes multiple systems. The Generator itself contains more than one system. We can divide the generator engine into mechanical and electronic divisions. Mechanical operations are monitored and controlled by the electronic control system. 

The engine spins the alternator and the alternator produces electricity to spin the grid. In most cases, the alternator operates trouble-free until the insulation breaks down between coil windings at the end of the alternator's life. It can be sent to a motor shop for rewinding or replaced with a new one.

The engine Electronic Control Module (ECM) or Electronic Control Unit (ECU) communicate with the main generator controller. An example of a controller is the Cummins PowerCommand Control series. The generator controller interfaces the engine controller with the generator to achieve the electrical demands of the complex. 

An Automatic Transfer Switch (ATS) changes states when power is lost and allows the generator to supply power to the building distribution panel(s). When utility power is restored, the ATS changes to a normal state and the building operates from utilities. 

Backup power distribution systems can range from a basic ATS and emergency supply circuit breaker to an advanced system that utilizes Wi-Fi, Bluetooth, cellular/landline, and remote monitoring/control abilities. Hospitals and large industrial complexes that have continuous power requirements often turn to multiple generators operated in parallel. The distribution system can include dedicated control rooms. These rooms contain many controls and switching panels. Generator paralleling and system control panels are common. 

When a technician responds to a power generator trouble call, he must possess the skills to select the correct system to begin the process with. The skilled technician has the ability to isolate the cause of the failed component or system. He will test the system to determine the cause, complete repairs, and test to ensure the failure has been repaired. Below are some examples of troubleshooting and ramifications of incomplete or incorrect troubleshooting.

Engine Over Temperature Shuts Generator Down

Louver Operating Mechanism
This is a fictional example of what can happen during the troubleshooting process and illustrates how the true cause of a failure can be masked. 

An engine technician receives a complaint that a generator shutdown during operation with the last utility power failure. The generator is an indoor application. When he arrives at the location, he reviews the electronic log for the cause of the shutdown. The coolant temperature data is valid but it is over specifications. Consulting the troubleshooting manual, the following steps are completed:
  1. Check Level - Checked coolant level of the coolant reservoir. No coolant needed. No coolant leaks visible.
  2. Check Fan Drive - Inspected fan drive for damage to belt area. No fan associated fault codes in history.
  3. Radiator Fins - Check for clogging and damage. No damage.
  4. Thermostat - Remove and test for full opening at an appropriate temperature. Install after testing.
  5. Coolant Pump - Inspect for a leak at weep hole. No leaks indicating seal damage.
  6. Fan Drive Belt - Inspect drive belt. Test drive belt tension. Tension does not meet specifications. Automatic tensioner and drive belt are replaced.
All fluid levels are checked, and the generator is started and run until it reaches operating temperature. The belt was inspected during operation and no problems were noted. 

During the next utility power failure, the generator is loaded and it shuts down during operation. A full-service generator repair company, Such as Generator Source, is contacted for a resolution. The technician verifies the work noted on the previous invoice. No engine cooling issues are apparent. A load tester is connected, and the generator is tested under load conditions. It shuts down during the test with a high coolant temperature. The louver drive motor position indicator shows only partial open of louvers. The louver motor is replaced and adjusted for a full louver open. The generator is load tested and maintains an appropriate coolant temperature.

The first repair attempt isolated a problem that could cause a coolant over temp issue but did not isolate the correct cause of the failure. The generator was not loaded to repeat the initial failure. The second repair technician load tested the generator before performing any repairs. In addition, he was well versed in generator auxiliary or support system interfaces.

Engine Fuel Pressure Shuts Generator Down

Day Tank Supplies Generator Engine Fuel
Again, this is a fictional example of incomplete or improper troubleshooting. Indoor applications are used because they offer more complex systems and the generator interfaces within normal operation.

A diesel engine technician is contracted to repair a problem that caused the generator to shut down during normal operation and will not start. A fuel pump pressurizing the fault code exists. Information indicates the primary time this happens is during loaded conditions. He completes the following steps in accordance with the manufacturer's manual:
  1. Air in Fuel - Performed air in fuel test. Fuel system contaminated with air. Removes air from the fuel system.
  2. Fuel Pressure Sensor - Inspect sensor and harness connector pins for damage dirty or damaged pins. Pins OK.
  3. Day Tank -Checked day tank fuel level. The level is correct.
  4. Testing - Starts and runs the engine. Engine runs without repeating fault code. Day tank level is appropriate with the engine running.
  5. Maintenance Records - Service completed to the engine just prior to a power outage.
The job is marked as complete with the possible cause as maintenance process. The generator loads during the next utility power failure and operates for part of the failure. Once again it shuts down. The generator technician from a full-service generator repair organization is contracted to troubleshoot the problem. Upon inspection, he finds that once again the fuel system has air. Air is removed from the fuel system. The day tank is full. He conducts a generator load test. The generator uses a maximum amount of fuel during this test. As the test progresses, the level indicator for the day tank continually falls. The load test is ended when the tank level reaches a minimum operating level.

Strainers are positioned between the primary fuel tank and the day tank. This strainer prevents debris from traveling to the day tank. The technician inspects the strainer and finds it to be contaminated with scale and debris. The fuel tank inspection indicates scaling. The tank is emptied and cleaned of scale. The original diesel fuel is filtered and added into the tank. The generator engine fuel filters are changed, and the generator is load tested. The day tank level maintains an appropriate fuel level throughout the duration of the test. 

The above troubleshooting issues are examples of the reasoning behind using a company that understands how auxiliary or supporting systems affect generator operation. Generator Source offers 35+ years of generator troubleshooting and repair. We have the ability to troubleshoot all generator and interfacing systems. Contact Us with any questions.


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