Knee voltage

Let Vs denote the knee voltage of the diodes. The transformer modulus in the piecewise linear model Sw Di of diode Dj, i = 1,..., 6, then reads... 

Knee Voltage Minimum forward bias volb e required for current flow, also sometimes called tbe threshold voltage, cut-in voltage, or forward voltage drop. 

These transformers develop a voltage on the secondary, substantially proportional to the voltage on the primary (there being no knee point saturation, as is sometimes required in CTs (Section I5,6.1(viii)),... 

These are protection CTs lor special applications such as biased differential protection, restricted ground fault protection and distance protection schemes, where it is not possible to easily identify the elass of accuracy, the accuracy limit factor and the rated burden of the CTs and where a full primary fault current is required to be transformed to the secondary without saturation, to accurately monitor the level of fault and/or unbalance. The type of application tind the relay being used determine the knee point voltage. The knee point voltage and the excitation current of the CTs now form the basic design parameters for such CTs. They are classified as class PS CTs and can be identified by the following characteristics ... 

Knee point voltage (kpv) at the maximum secondary turns,... 

Excitation current at knee point voltage (or at any other required voltage or both) (A) 0.05... 

This is a voltage close to the knee-point of the characteristic. It is a point where it commences its conduction and draws a current, resistive in nature, in the range of a few mA. Typical values are 0.4-10 mA. 

Nominal CT ratio. This may be such that on the smallest ground fault the current on the secondary is sufficient to operate the relay. Normal /p = 50, 100 and 200 A. It is recommended to be such that V, = 0.1 x knee point voltage of the CBC F... 

Figure 24. Typical power curve for a fuel cell. The voltage drops quickly from the OCV due to the formation of the peroxide intermediate. Operation of the fuel cell at the knee of the curve where concentration is limiting performance can damage the electrodes and lead to rapid deterioration of cell operation.

Krueger, E., Scheeren, E.M., Nogueira-Neto, C.N., Neves, E.B. et al., Relationship between peak and mean amplitudes of the stimulating output voltage for functional control of the knee by spinal cord patients and healthy volunteers. Rev. Bras. Eng. Biomidica, 29, pp. 144-152, 2013. 

In practice, the measurement is especially sensitive when the chemical term Ay, generally smaller than one volt, is accurately measurable. This cannot be the case when cell voltages of several hundred volts are used When the "waves are not easily detectable because of too high cell voltage, the method may be still appropriate if the coloration is accompanied by a drastic electric resistance variation. The passage of the coloration front is then evidenced by a knee on the E(t) plot (cf. formulae 101). 

In the present study, a knee joint simulator is used to simulate the tibial axis load and flexion-extension motion under walking condition. The lubrication condition or fluid film formation in knee prosthesis models is evaluated by measuring the electric contact resistance between the femoral metallic component and tibial conductive polymeric or elastomeric component under the constant applied voltage in a knee joint simulator. 

The coupled hierarchical model was evaluated by comparison with experimental data of Suzuki et al. (2011) and Soboleva et al. (2011). Both of these studies provided experimental data on CL structure as well as electrochemical performance, which were used to parameterize the model. The pore size distributions of the catalyst layers are depicted in Figure 3.42. Figure 4.12a shows polarization curves from both experimental studies compared to the curves obtained from the hierarchical model. Experimental trends are reproduced within the model. It is evident that flooding of the GDL is responsible for the knee in fuel cell voltage at high current density. 

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