E-34 — Policy on demand measurement established using a demand interval length other than the programmed demand interval length
The copy of this document located on Measurement Canada's website is considered to be the controlled copy.
Document(s): LMB-EG-07, S-E-06 and E-30
Table of contents
The purpose of this bulletin is to provide Measurement Canada's (MC) policy on demand measurements that are established using a demand interval length other than the programmed demand interval length.
This bulletin applies to all electricity meters which are used to establish the basis of a charge for demand in legal units of measure.
- LMB-EG-07, "Specifications for Approval of Type of Electricity Meters, Instrument Transformers and Auxiliary Devices"
- Specification, "S-E-06—Specification for the Approval of Type of Electricity Meters and Auxiliary Devices – Amendments to Measurement Canada Specification LMB-EG-07"
MC has recently discovered that the demand interval length of certain approved electricity meters can be modified under certain operating conditions or events (e.g., when an over-the-air remote adjustments is made to the real-time clock or during power down and power up, time-of-use rate changes, activation and deactivation of certain meters modes, etc.). Under these conditions, the demand interval length is temporarily changed such that the energy registered for the purpose of establishing demand is gathered over an interval which may be less than 15 minutes in length. This results in non-compliance with the approval requirement of clause 5.15.3 of specification S-E-06, which prescribes that the demand interval be not less than 15 minutes.
MC considers the practical manifestation of this non-compliance to be important, as it affects numerous meters in Canada. The Agency has issued an amendment to Bulletin E-30 to clarify the intent of the above-mentioned approval requirement and its applicability to the meter. An installation and use specification may be issued in the future to prescribe requirements for the establishment of demand values outside an approved electricity meter in a manner that complies with this policy.
Manufacturers have reported that most existing meters have been designed with features which mitigate the impact of a shortened demand interval length on registered demand values. Therefore, as this will not disadvantage consumers, MC has decided to permit the occurrence of temporary adjustments to demand intervals subject to the conditions listed in this bulletin.
5.1 In the case of meters that establish demand using a demand interval length other than the programmed interval, the demand registration will be deemed acceptable on condition that:
- the meter discards any demand measurement which is established on the basis of energy data accumulated over an interval which is either shorter or longer than the programmed interval or;
- where the energy data is accumulated over an interval of less than 15 minutes, the demand value is calculated using the energy data as if it was registered over the actual programmed demand interval (typically 15 minutes).
5.2 In the case of meters that establish demand on the basis of sliding window algorithms, the provisions of 5.1 shall apply to the subinterval. In addition, the calculation for sliding window demand shall be based on contiguous running time subinterval data. Demand measurements subsequent to a power outage lasting greater than a complete subinterval shall be determined as if the previous two subintervals contained no energy data.
5.3 Manufacturers are responsible for identifying meters which have reprogrammable clocks and providing a written statement of their compliance status to MC's Electricity Approval Services Laboratory. They shall also communicate the existence of any manufactured meters that are not compliant with the requirements of this bulletin.
5.4 Meter owners will not be required to make changes to approved and verified meters already in service as of the effective date of this bulletin, where these meters incorporate the design characteristics described in section 5. MC has concluded that, given the low risk to electricity consumers, removal of such meters in not warranted.
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