Common use of Stability criteria Clause in Contracts

Stability criteria. To evaluate the influence of operating conditions on the cell/stack performance, a certain degree of stability of both TIPs and TOPs is required. One simple option to evaluate stability is to record a parameter with a desired sampling rate for a desired sampling duration. The parameter is considered stable if the maximum variation (difference between the maximum value and the minimum value recorded) does not exceed a pre-defined threshold value. However, it is difficult to give a generic definition of the sampling rate, sampling duration and variation threshold. This is due to the fact that each individual TIP may have a different impact on the cell/stack performance. If the cell/stack performance is not so sensitive to a TIP, it is then acceptable to set a larger variation threshold for that TIP. A parameter sensitivity investigation needs thus to be performed to define precisely the stability criteria. In addition, the measurement uncertainty of TOPs should also be taken into account for the definition of stability criteria. Furthermore, in many cases a compromise needs to be found between good stability and reasonable test duration. A very strict stability criterion may not be fulfilled due to the time constraint. Nevertheless, the following stability criteria in Table 3 can be taken as a reference and can be adapted according to the test object, test system and test objective. Vcell, VRU,i 1 Hz 3 min 5 mV (SOFC mode) 10 mV (SOEC mode) I 1 Hz 3 min 0.5 A T 1 Hz 3 min 1 K fneg/pos, in/out 1 Hz 3 min 3% FS pneg/pos, in/out 1 Hz 3 min 3% FS