The ESC test cycle (also known as OICA/ACEA cycle) has been introduced, together with the ETC (European Transient Cycle) and the ELR (European Load Response) tests, for emission certification of heavy-duty diesel engines in Europe starting in the year 2000 (Directive 1999/96/EC of December 13, 1999). The ESC is a 13-mode, steady-state procedure that replaces the R-49 test.
The engine is tested on an engine dynamometer over a sequence of steady-state modes (Table 1, Figure 1). The engine must be operated for the prescribed time in each mode, completing engine speed and load changes in the first 20 seconds. The specified speed shall be held to within ±50 rpm and the specified torque shall be held to within ±2% of the maximum torque at the test speed. Emissions are measured during each mode and averaged over the cycle using a set of weighting factors. Particulate matter emissions are sampled on one filter over the 13 modes. The final emission results are expressed in g/kWh.
During emission certification testing, the certification personnel may request additional random testing modes within the cycle control area (Figure 1). Maximum emission at these extra modes are determined by interpolation between results from the neighboring regular test modes.
| Mode | Engine Speed | % Load | Weight factor, % | Duration |
|---|---|---|---|---|
| 1 | Low idle | 0 | 15 | 4 minutes |
| 2 | A | 100 | 8 | 2 minutes |
| 3 | B | 50 | 10 | 2 minutes |
| 4 | B | 75 | 10 | 2 minutes |
| 5 | A | 50 | 5 | 2 minutes |
| 6 | A | 75 | 5 | 2 minutes |
| 7 | A | 25 | 5 | 2 minutes |
| 8 | B | 100 | 9 | 2 minutes |
| 9 | B | 25 | 10 | 2 minutes |
| 10 | C | 100 | 8 | 2 minutes |
| 11 | C | 25 | 5 | 2 minutes |
| 12 | C | 75 | 5 | 2 minutes |
| 13 | C | 50 | 5 | 2 minutes |
Figure 1. European Stationary Cycle (ESC)
The engine speeds are defined as follows:
- The high speed nhi is determined by calculating 70% of the declared maximum net power. The highest engine speed where this power value occurs (i.e. above the rated speed) on the power curve is defined as nhi.
- The low speed nlo is determined by calculating 50% of the declared maximum net power. The lowest engine speed where this power value occurs (i.e. below the rated speed) on the power curve is defined as nlo.
- The engine speeds A, B, and C to be used during the test are then calculated from the following formulas:
A = nlo + 0.25(nhi - nlo)
B = nlo + 0.50(nhi - nlo)
C = nlo + 0.75(nhi - nlo)
The ESC test is characterized by high average load factors and very high exhaust gas temperatures.