Russell.1508
Member
Has to be implemented on CX Programmer
Under PAHH conditions the logic solver closes the S-ESD inlet valve and keeps the S-ESD outlet valve open.
a. The PAHH pressure is 1800 psi.
b. The PT provides a 4-20mA output signal related linearly to a pressure range of 0 to
2000 psi. The load resistor used at the PLC for the PT 4-20mA input is 500Ω.
c. The PT has an accuracy (3σ) of ±0.5 % FS (max).
d. The PLC analogue input module has a voltage input range of 0-10V.
e. The total current noise on the PT analogue line is expected to be a frequencies above
2Hz. Provide ladder logic for a first order digital low pass filter to reject this noise to avoid false PAHH tripping. A simple moving average filter that can be considered for this purpose is an exponentially weighted moving average (EWMA) filter for which
y[k]=ax[k]+(1−Alpha)y[k−1], 0≤Alpha≤1
This filter produces an output y[k] which is a scaled average of the current input, x[k], and the previous output, y[k-1]. The coefficient, α, is related to the constant time between successive sampled inputs, T (seconds), together with the filters cut-off frequency
Please help have no clue how
Under PAHH conditions the logic solver closes the S-ESD inlet valve and keeps the S-ESD outlet valve open.
a. The PAHH pressure is 1800 psi.
b. The PT provides a 4-20mA output signal related linearly to a pressure range of 0 to
2000 psi. The load resistor used at the PLC for the PT 4-20mA input is 500Ω.
c. The PT has an accuracy (3σ) of ±0.5 % FS (max).
d. The PLC analogue input module has a voltage input range of 0-10V.
e. The total current noise on the PT analogue line is expected to be a frequencies above
2Hz. Provide ladder logic for a first order digital low pass filter to reject this noise to avoid false PAHH tripping. A simple moving average filter that can be considered for this purpose is an exponentially weighted moving average (EWMA) filter for which
y[k]=ax[k]+(1−Alpha)y[k−1], 0≤Alpha≤1
This filter produces an output y[k] which is a scaled average of the current input, x[k], and the previous output, y[k-1]. The coefficient, α, is related to the constant time between successive sampled inputs, T (seconds), together with the filters cut-off frequency
Please help have no clue how
