Power system disturbance report

See monthly power quality report

What is power quality monitoring?

Monitoring the voltage or current phases for conditions that could have adverse affect on on electrical equipment. This report presents power quality disturbance records that have been captured by EWEB's power quality monitors. The report's format allows users to quickly interpret power quality problems. The report is broken into 2 sections:

Summary Sheet: Provides an overview of the worst power quality "Incidents". Power quality "Incidents" are sorted according to severity with the worst incidents listed first. Each Incident is also plotted on a Information Technology Industry Council (ITIC) curve, which is described below.

Incident Sheets: Each Incident is described in more detail.

Summary sheet

Every Incident shown in the Summary sheet is a grouping of one or more Disturbances. This arrangement provides a summary view of power quality by grouping Disturbances associated with a single power system

Incident: For example, the Incident of a car striking a power pole might trigger several Disturbances to be recorded by power monitors connected at various locations in the power grid. However, only the worst Disturbance from the whole Incident is shown in the Summary Sheet. Incident: An incident is physical occurrence (like a lightning strike or a car hitting a telephone pole) that causes the power monitor(s) to report PQ disturbances. An incident is presented as collection of disturbances that occurred within a programmable period of time. Disturbance: A disturbance occurs when a power monitor records a voltage sag, swell or transient that exceeds a set threshold.

Incident severity: Incidents are sorted by severity. The severity of an Incident is defined by the severity of the worst Disturbance contained in that Incident. Disturbance severity is calculated as: ABS((100-disturbance magnitude as % of nominal) * disturbance duration) The higher the number the worse the disturbance. For example, a disturbance on phase A with duration of 1 second and magnitude of 85% is considered more severe than a disturbance on phase C with a duration of 1 second and a magnitude of 92%.

Incident sheets

Each Incident sheet lists the Disturbances that are part of the Incident. The worst Disturbance is shown italicized This is also the Disturbance that is recorded on the Summary Sheet. Each Disturbance is plotted on a ITIC curve. Meter Configuration: Each Incident Sheet displays the meter configuration for the disturbances that it contains. There are three sections of meter configuration information:

  • Meter Information - contains the values of the PT primary, PT secondary, CT primary, CT secondary and the Nominal Voltage for each meter that detected a Disturbance. This information is contained in the transient logs, so will only be displayed if transient information is available for that meter.
  • Transient Configuration - contains the transient detection threshold for each meter that detected a voltage transient.
  • Sag/Swell Configuration - contains the sag and swell detection thresholds for each meter that detected a voltage sag or swell.
Power tolerance curves

The power tolerance curve that is used throughout this report is the 1996 ITIC curve, formerly known as the CBEMA curve. The ITIC curve plots the magnitude of the disturbance (in percentage) on the Y-axis and the duration of the disturbance on the X-axis. Disturbances that fall within the envelope defined by the upper and the lower curve are typically not harmful to electrical equipment; disturbances that fall outside the envelope may disrupt or damage the equipment.