Commission Delegated Regulation (EU) 2017/655Show full title

Appendix 3

Data pre-processing for gaseous pollutant emissions calculations U.K.

1. Definitions U.K.

1.2. For the purposes of this Appendix the following definitions shall apply: U.K.

1.2.1.

‘zero response’ means the mean response, including noise, to a zero gas during a time interval of at least 30 seconds;

1.2.2.

‘span response’ means the mean response, including noise, to a span gas during a time interval of at least 30 seconds.

2. Drift correction U.K.

2.1. Maximum drift allowed U.K.

Drifts of the zero response and the span response shall be less than two per cent of full scale on the lowest range used:

(a)

if the difference between the pre-test and post-test results is less than two per cent, the measured concentrations may be used uncorrected or may be corrected for drift according to point 2.2;

(b)

if the difference between the pre-test and post-test results is equal to or greater than two per cent, the measured concentrations shall be drift corrected according to point 2.2. If no correction is made, the test shall be considered void.

2.2. Drift correction U.K.

The drift corrected concentration value shall be calculated in accordance with the requirements set out in Section 2.1 or Section 3.5 of Annex VII to Delegated Regulation (EU) 2017/654.

The difference between the uncorrected and the corrected brake-specific gaseous pollutant emission values shall be within ± six per cent of the uncorrected brake-specific gaseous pollutant emission values. If the drift is greater than six per cent, the test shall be considered void.

If drift correction is applied, only the drift-corrected gaseous pollutant emission results shall be used when reporting gaseous pollutant emissions.

3. Time alignment U.K.

To minimise the biasing effect of the time lag between the different signals on the calculations of the mass of the gaseous pollutant emissions, the data relevant for gaseous pollutant emissions calculations shall be time aligned, in accordance with the requirements set out in points 3.1 to 3.4.

3.1. Gas analysers data U.K.

The data from the gas analysers shall be properly aligned in accordance with the requirements set out in Section 8.1.5.3 of Annex VII to Delegated Regulation (EU) 2017/654.

3.2. Gas analysers and EFM data U.K.

The data from the gas analysers shall be properly aligned with the data of the EFM using the procedure set out in point 3.4.

3.3. PEMS and engine data U.K.

The data from the PEMS (gas analysers and EFM) shall be properly aligned with the data from the engine ECU using the procedure in point 3.4.

3.4. Procedure for improved time alignment of the PEMS data U.K.

The test parameters listed in the Table of Appendix 2 are split into three different categories:

• Category 1: Gas analysers (HC, CO, CO₂, NO_x concentrations);

• Category 2: EFM (Exhaust mass flow and exhaust temperature);

• Category 3: Engine (Torque, speed, temperatures, fuel rate from ECU).

The time alignment of each category with the other two categories shall be verified by finding the highest correlation coefficient between two series of test parameters. All the test parameters in a category shall be shifted to maximise the correlation factor. The following test parameters shall be used to calculate the correlation coefficients:

(a)

Categories 1 and 2 (Gas analysers and EFM data) with Category 3 (Engine data): from the ECU;

(b)

Category 1 with Category 2: the CO₂ concentration and the exhaust mass flow;

(c)

Category 2 with Category 3: the CO₂ concentration and the engine fuel flow.

4. Data consistency check U.K.

4.1. Gas analysers and EFM data U.K.

The consistency of the data (exhaust mass flow measured by the EFM and gas concentrations) shall be verified using a correlation between the measured engine fuel flow from the ECU and the engine fuel flow calculated in accordance with the procedure set out in Section 2.1.6.4 of Annex VII to Delegated Regulation (EU) 2017/654.

A linear regression shall be performed for the measured and calculated fuel rate values. The method of least squares shall be used, with the best fit equation having the form:

y = mx + b

Where:

• y is the calculated fuel flow [g/s],

• m is the slope of the regression line,

• x is the measured fuel flow [g/s],

• b is the y intercept of the regression line.

The slope (m) and the coefficient of determination (r²) shall be calculated for each regression line. It is recommended to perform this analysis in the range from 15 per cent of the maximum value to the maximum value and at a frequency greater or equal to 1 Hz. For a test to be considered valid, the following two criteria shall be evaluated:

[F1 Table

Tolerances

Slope of the regression line, m	0,9 to 1,1 – Recommended
Coefficient of determination, r 2	min. 0,90 – Mandatory]

Textual Amendments

F1 Substituted by Commission Delegated Regulation (EU) 2018/987 of 27 April 2018 amending and correcting Delegated Regulation (EU) 2017/655 supplementing Regulation (EU) 2016/1628 of the European Parliament and of the Council with regard to monitoring of gaseous pollutant emissions from in-service internal combustion engines installed in non-road mobile machinery (Text with EEA relevance).

4.2. ECU torque data U.K.

The consistency of the ECU torque data shall be verified by comparing the maximum ECU torque values at different (if appropriate) engine speeds with the corresponding values on the official engine full load torque curve and in accordance with Appendix 6.

4.3. Brake-Specific Fuel Consumption (BSFC) U.K.

The BSFC shall be checked using:

(a)

the fuel consumption calculated from the gaseous pollutant emissions data (gas analysers concentrations and exhaust mass flow data), in accordance with the procedure set out in Section 2.1.6.4 of Annex VII to Delegated Regulation (EU) 2017/654;

(b)

the work calculated using the data from the ECU (Engine torque and engine speed).

4.4. Ambient pressure U.K.

The ambient pressure value shall be checked against the altitude indicated by the GPS data, if available.

4.5. The approval authority may consider the test void if it is not satisfied with the results of the data consistency check. U.K.

5. Dry-wet correction U.K.

If the concentration is measured on a dry basis, it shall be converted to a wet basis in accordance with the procedure set out in Section 2 or Section 3 of Annex VII to Delegated Regulation (EU) 2017/654.

6. NO_x correction for humidity and temperature U.K.

The NO_x concentrations measured by the gas analysers shall not be corrected for ambient air temperature and humidity.