- A PQIncidenstTM occurs when one or more of the PQ parameters exceeds a specification or causes a problem for a load
- A PQIncidenstTM is comprised of one or more events
- A PQIncidentsTM is a definable point in time and power quality characteristic
- Most PQIncidentsTM are associated with significant changes in the voltage at the utility level
Sources of PQIncidentsTM
- Equipment failure
- Phase to ground short circuits
- Fuses clearing/breakers tripping
- Loads switching
- Is the presence of voltage at the meter point. (measured to approx. 1 to 2 sec)
- Depends on the utility
- Depends on the contract for power reliability and Power Quality
- The values of the various PQ parameters at the meter point. ( less than 1 to 2 sec)
- The effect on the operation of the factory or a piece of equipment. IE elevator, computer, process controller etc
- The effect on the electrical system of power polluting loads
What are the various PQ parameters?
- Voltage sags (dips) low line voltage (brown outs) RMS values
- Voltage waveform events (subcycle)
- Voltage transients (fast spikes)
- Voltage imbalance
- Interruptions planned or unplanned
- Other Wiring and Construction (design)
- Review the customer input and form.
- Review RMS graphs of the values of all PQ parameters.
- Review the PQ event data
- Identify time of day and date of occurrence
Characterize the PQIncidentsTM
- Determine the duration and magnitude
- Determine the source (load caused?)
- Determine if the source can be prevented
- Determine if an auxiliary power source is needed to “fill in the energy loss”
- Document the PQIncidentsTM, the source and solution
Why use PQIncidentsTM?
- Reduce data to manageable sizes
- Clear the fog on events
- Focus on the major issues first.
- Solve the major problems and the minor ones may not matter
General ITIC curve (1997)
11 kVA CBEMA PQIncidentsTM
- PQIncidentsTM summarizes the data
- Provides a simple model for economic analysis