Step Testing

import matplotlib.pyplot as plt
import pandas as pd

from tclab import TCLab, clock, Historian, Plotter

Run the next cell if you only want to simulate TCLab

from tclab import setup
TCLab = setup(connected=False, speedup=20)

Executing the Step Test

Verify an Initial Steady State

A step test assumes the system is initially at steady state. In the case of the Temperature Control Lab, the initial steady with no power input would be room temperature. It generally takes 10 minutes or more to reach steady state. We’ll do a measurement to confirm the initial temperature.

lab = TCLab()
print(lab.T1, lab.T1)
lab.close()

TCLab version 1.0.0
Simulated TCLab
20.949499999999997 20.949499999999997
TCLab Model disconnected successfully.

Conduct the Experiment

# experimental parameters
Q1 = 50
tfinal = 800

# perform experiment
with TCLab() as lab:
    h = Historian(lab.sources)
    p = Plotter(h, tfinal)
    lab.Q1(0)
    for t in clock(tfinal):
        p.update(t)
        lab.Q1(Q1)

TCLab Model disconnected successfully.

Verify the experimental data

h.columns

['Time', 'T1', 'T2', 'Q1', 'Q2']

try:
    t = h.t
    T1 = h.T1
    T2 = h.T2
    Q1 = h.Q1
    Q2 = h.Q2
except:
    t, T1, T2, Q1, Q2 = h.fields
    
plt.plot(t, T1, t, T2, t, Q1, t, Q2)
plt.legend(['T1','T2','Q1','Q2'])
plt.xlabel('time / seconds')
plt.grid()

Convert to a DataFrame

import pandas as pd

df = pd.DataFrame([t, T1, T2, Q1]).T
df.columns = ['Time', 'T1', 'T2', 'Q1']
df = df.set_index('Time')
df.plot(grid=True)

Save DataFrame as a .csv file

df.to_csv('Step_Test_Data.csv')

Verify the data file

pd.read_csv('Step_Test_Data.csv').set_index('Time').plot(grid=True)

df.head()

	T1	T2	Q1
Time
0.00	20.6272	20.6272	0.0
9.00	20.9495	20.9495	50.0
10.00	20.9495	20.9495	50.0
12.01	20.9495	20.9495	50.0
13.00	20.9495	20.9495	50.0

df.tail()

	T1	T2	Q1
Time
795.01	50.6011	25.784	50.0
796.00	50.6011	25.784	50.0
798.01	50.6011	25.784	50.0
799.01	50.6011	25.784	50.0
800.01	50.6011	25.784	50.0