Dc Responses To Test Cells; Ac Responses To Test Cells - Ametek Solartron Analytical ModuLab XM ECS Installation Manual

Installation Tests
3.2.1 Time Domain/DC Responses to Test Cells
The ModuLab Test Cell has a circuit made up of resistors and capacitors, and the
circuit diagram is printed on the cover (Figure 3-1).
This circuit is effectively a series of resistors when a DC voltage is applied, with
a total resistance of 11.6kΩ. The relationship between voltage and current is a
straight line, with the slope representing the resistance of the cell as shown in
Figure 3-3.
Figure 3-3
The ModuLab 0.1 ohm Cell has a circuit made up of only a single resistor, and
the circuit diagram is printed on the cover (Figure 3-2). The response to a DC
input is a straight line, same as in Figure 3-3 except that the resistance is 0.1 ohm.
3.2.2

AC Responses to Test Cells

When an AC voltage is applied to a test cell, the relationship between voltage and
current is represented by the impedance which has a real component Z and an
imaginary component Z, giving the complex impedance Z
magnitude |Z| and phase angle , which are all dependent on frequency. The
relationships between these values are as follows:
= Z – j Z
*
Z
where j = √-1
|Z| = √ (Z
 = tan
The results of AC measurements are normally represented in two ways:
• A Bode plot of impedance magnitude |Z| and phase angle against
frequency.
•
A complex plane plot of the real and imaginary components of impedance, Z
and Z.
3-4
ModuLab XM ECS Electrochemical System: Installation Guide
Response of ModuLab Test Cell to DC input
2 2
+ Z )
-1
( Z / Z )
*
, the impedance
21006002_AD 11/06/14