Question and Answers
What is Non-Consequential Load Loss (NCLL)?
The North American Reliability Corporation (NERC) defines NCLL as “Non-Interruptible Load loss that does not include: (1) Consequential Load Loss, (2) the response of voltage sensitive Load, or (3) Load that is disconnected from the System by end-user equipment.” (NERC Glossary of Terms)
NB Power uses NCLL in the form of Under Voltage Load Shedding (UVLS) to help prevent low voltage conditions on its power system. UVLS devices detect low voltages and quickly shut off the power to associated power lines to minimize potential equipment damage that may result from operating at low voltages. When UVLS operates for outages that occur on lines other than the line that gets shut off, the load loss is deemed to be “non-consequential” in that it was not a consequence of a problem on the line that was shut off.
How does planned use of NCLL impact me as an NB Power customer?
You may experience a power outage due to the operation of UVLS equipment that will protect your home or business’s equipment from possible damage due to low voltages.
What areas are affected by the planned use of NCLL on NB Power’s system
The affected areas include the Manawagonish substation in western Saint John, the Eastern Maine Electric Cooperative (EMEC) system in southeastern Maine, and the Pennfield terminal in southwest New Brunswick which supplies the St. George, Deer Island, Campobello, and Grand Harbour substations.
Why is NB Power choosing planned use of NCLL instead of building more lines or adding more equipment to avoid the risk of low voltages?
NB Power is choosing planned use of NCLL for the areas identified because the low risk of NCLL in these instances doesn’t justify the added costs to the system. The costs incurred would be approximately $1.5 million at both the Manawagonish substation and the Pennfield terminal.
Why does NB Power say there is a low risk of NCLL?
NB Power estimates that planned use of NCLL at Manawagonish will only occur once in 17,900 years. In the case of the Pennfield Terminal, the planned use of NCLL would occur once in every 86 years.
Is NB Power using NCLL today at the Manawagonish substation, the EMEC, and the Pennfield terminal?
NCLL is not currently used at Manawagonish. However, it will be required in 2023 for efforts relating to the system changes being made by Saint John Energy with respect to the Burchill Wind Farm and the 66 kV substation development.
NB Power currently uses NCLL in the form of UVLS for the EMEC circuit in Maine (installed by 1989) and at the Pennfield terminal (installed in 2003).
Has NB Power ever had an NCLL related UVLS operation in the areas where they wish to continue its planned use?
NB Power’s outage records date back to 1992. There have been no UVLS operations recorded on the relevant circuits since that time.