S-E-09 — Specification for the Approval of Type of 80 mA and 100 mA class Measuring Current Transformers

0.9955 0.9970 0.9985 1.0000 1.0015 1.0030 1.0045 -20 -15 -10 -5 0 5 10 15 20 Ratio connection factor ← Lagging Phase angle - minutes Leading → 0.15 accuracy class Scale: 1% = 0.01 RCF = 34.4 min = 1 crad 0.991 0.994 0.997 1.000 1.003 1.006 1.009 -40 -30 -20 -10 0 10 20 30 40 Ratio connection factor ← Lagging Phase angle - minutes Leading → 0.3 accuracy class Scale: 1% = 0.01 RCF = 34.4 min = 1 crad 0.982 0.988 0.994 1.000 1.006 1.012 1.018 -80 -60 -40 -20 0 20 40 60 80 Ratio connection factor ← Lagging Phase angle - minutes Leading → 0.6 accuracy class Scale: 1% = 0.01 RCF = 34.4 min = 1 crad

Category: Electricity
Specification: S-E-09
Document(s): S-E-07 and LMB-EG-07
Issue Date: 2010-04-27
Effective Date: 2010-04-27


Table of Contents


1.0 Scope

This specification applies to 80 milliampere (mA) Current Transformers (CT) and 100 milliampere (mA) Current Transformers (CT) which are intended to be used in revenue metering.

2.0 Authority

This specification is issued pursuant to subsection 12 (1) of the Electricity and Gas Inspection Regulations.

3.0 References

  • Electricity and Gas Inspection Act (R.S. 1985, c. E-4), ss. 9(4).
  • Electricity and Gas Inspection Regulations (SOR/86-13), ss. 12(1).
  • Measurement Canada, LMB-EG-07: Specifications for the Approval of Type of Electricity Meters, Instrument Transformers, and Auxiliary Devices.
  • Measurement Canada, S-E-07: Specifications for the Approval of Measuring Instrument Transformers.
  • IEEE Std C57.13-2008: IEEE Standard Requirements for Instruments Transformers.
  • CAN-CSA 60044-X:07 series: Instrument Transformers series.

4.0 Definitions

Applicable definitions can be found in Measurement Canada (MC) S-E-07.

5.0 General Requirements

All requirements specified in MC specifications S-E-07 shall be applicable to the 80 mA and 100 mA class CT in addition to the following requirements.

6.0 Ratings

6.1 Current rating of 80 mA class measuring CT shall be according to the values in Table 1 below.

Table 1 - Current rating for 80 mA class measuring CT
Primary Current (A) Secondary Current (mA) Ratio
5 80 62.5:1
100 80 1250:1
200 80 2500:1
400 80 5000:1

6.2 Current rating of 100 mA class measuring CT shall be according to the values in Table 2 below.

Table 2 - Current rating for 100 mA class measuring CT
Primary Current (A) Secondary Current (mA) Ratio
5 100 50:1
100 100 1000:1
200 100 2000:1
400 100 4000:1
600 100 6000:1
800 100 8000:1

7.0 Rated Burden

7.1 Standard burdens for 80 mA class CT shall be according to the values in Table 3 below.

Table 3 - Standard burdens for 80 mA class measuring CT
Standard Burden Characteristics Characteristics for 60 Hz 0.08A Secondary Current
Resistance (ohm) Inductance (mH) Impedance (ohm) V*A PF
B0.005 17.6 23 20 0.125 0.9
B0.01 35.2 45 39 0.25 0.9
B0.03 105.5 135 117 0.75 0.9
B0.05 176 226 195 1.25 0.9

7.2 Standard burdens for 100 mA class CT shall be according to the values in Table 4 below.

Table 4 - Standard burdens for 100 mA class measuring CT
Standard Burden Characteristics Characteristics for 60 Hz 0.1A Secondary Current
Resistance (ohm) Inductance (mH) Impedance (ohm) V*A PF
B0.005 11.3 14 13 0.125 0.9
B0.01 22.5 29 25 0.25 0.9
B0.03 67.5 87 75 0.75 0.9
B0.05 112.5 145 125 1.25 0.9

8.0 Accuracy

8.1 Assignment of Accuracy Class - A measuring mA current transformer shall be given an accuracy class as specified in Table 5 for each standard burden, (Tables 3 and 4), up to the maximum for which it is designed.

8.2 Basis for Measurement Accuracy Classes - Accuracy classes for mA measuring CT are based on the requirement that the transformer correction factor (TCF) shall be within specified limits for the following conditions:

  1. 100% of rated primary current or the corresponding continuous current factor
  2. 10% or 5% of rated primary current
  3. Power factor (lagging) of metered power load from 0.6 to 1.0
  4. Burden of a specific standard value
  5. Normal service conditions

Note: At 5% or 10% of rated primary current, the permissible error is twice the error at 100% rated primary current.

The relationships between the limits of the ratio correction factors (RCFs) and the phase angle for the limiting values of the TCFs specified in Table 5 are shown in the parallelograms in Figure 1.

Table 5 - Accuracy Classes and Corresponding Limits of Transformer Correction Factors for Measuring Current Transformers
Accuracy Class 100% rated current* 10% rated Current 5% rated current Limits of power factor (lag) of metered power load
0.15 0.9985–1.0015 - 0.997–1.003 0.6–1
0.3 0.997–1.003 0.994–1.006 - 0.6–1
0.6 0.994–1.006 0.988–1.012 - 0.6–1

Note:

  1. These limits also shall be applicable at the maximum continuous current rating factor (RF)
  2. 5A:80mA 5A:100mA rating CT shall not be approved for accuracy class other than 0.15%

Figure 1–Limits for measuring current transformer

Limits of 0.15 accuracy class
Description of limits of 0.15 accuracy class figure

The relationships between the limits of the ratio correction factors and the phase angle for the limiting values of the transformer correction factors (TCFs) specified in Table 5 are provided by parallelograms that are plotted on graphs in which a phase angle correction factor in minutes appears on the x-axis and a ratio correction factor appears on the y-axis. The parallelograms defining the limiting values of the TCFs for current transformers are bound by vertices. For a 0.15 accuracy class at a 5% rated current, the limiting values are (0, 1.003), (15.6, 1.003), (0, 0.997) and (-15.6, .997). At a 100% rated current, the limiting values are (0, 1.0015), (7.8, 1.0015), (0, 0.9985) and (-7.8, 0.9985).

Limits of 0.3 accuracy class
Description of imits of 0.3 accuracy class figure

The relationships between the limits of the ratio correction factors and the phase angle for the limiting values of the transformer correction factors (TCFs) specified in Table 5 are provided by parallelograms that are plotted on graphs in which a phase angle correction factor in minutes appears on the x-axis and a ratio correction factor appears on the y-axis. The parallelograms defining the limiting values of the TCFs for current transformers are bound by vertices. For a 0.3 accuracy class at a 10% rated current, the limiting values are (0, 1.006), (31.2, 1.006), (0, 0.994) and (-31.2, 0.994). At a 100% rated current, the limiting values are (0, 1.003), (15.6, 1.003), (0, 0.997) and (-15.6, 0.997).

Limits of 0.6 accuracy class
Description of limits of 0.6 accuracy class figure

The relationships between the limits of the ratio correction factors and the phase angle for the limiting values of the transformer correction factors (TCFs) specified in Table 5 are provided by parallelograms that are plotted on graphs in which a phase angle correction factor in minutes appears on the x-axis and a ratio correction factor appears on the y-axis. The parallelograms defining the limiting values of the TCFs for current transformers are bound by vertices. For a 0.6 accuracy class at a 10% rated current, the limiting values are (0, 1.012), (62.4, 1.012), (0, 0.988) and (−62.4, 0.988). At a 100% rated current, the limiting values are (0, 1.006), (31.2, 1.006), (0, 0.994) and (−31.2, 0.994)

9.0 Additional Information

For additional information regarding this specification, please contact the Senior Program Officer responsible for electricity measurement.

Alan E. Johnston
President

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