Electrical Testing of Electrodes and Shafts

Last Updated: 9/10/19 by Tim Paschkewitz

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1Overview

This document describes the procedure for testing the electrical connections of shafts, rotating ring-disk electrode tips, rotating cylinder electrodes, and rotating disk electrode tips. These simple tests can help isolate electrical problems with electrode instrumentation. Electrical problems can arise as a result of accidental damage (e.g., dropping the tip or shaft from a significant height, such as rolling off the lab bench) or in some cases, can arise from heavy chemical contamination and/or corrosion. This document describes how to make some electrical measurements of shafts and electrodes. These tests can be performed with a simple multimeter by measuring the resistance across two probes.

2Electrical Isolation Guide

The document herein uses three colors (red, blue, and green) to differentiate electrically isolated sections of rotating ring-disk electrodes (RRDEs), rotating cylinder electrodes (RCEs), and rotating disk electrodes (RDEs). The three colors are also used to differentiate the electrically-isolated sections of their respective shafts. Red corresponds to the section of the shaft that connects to the rotator, blue corresponds to the section of the electrode/shaft that connects to and controls the disk or cylinder, and green corresponds to the section of the electrode/shaft that connects to and controls the ring. Additionally, letters A-F are used to describe distinct sections of a shaft or electrode (see Table 1).

Letter	Color	Description
A	Red	Rotator connection section of shaft (electrically-isolated)
B	Blue	Disk/cylinder electrical connection section of shaft
C	Green	Ring electrical connection section of shaft
D	Blue	Disk electrical connection section of an RDE/RRDE tip
E	Blue	RDE and/or RRDE electrode tip disk/RCE cylinder
F	Green	Ring electrical connection section of an RRDE tip
G	Green	RRDE electrode tip ring

Table 1. Description of Color and Letter Used to Describe Electrically-Isolated Sections.

If any of the test measurements are not as described in this document, contact Pine Research to discuss the test results. In some cases, the tip and/or shaft may be irreversibly damaged and must be replaced. In other cases, our production team may be able to attempt a repair. In the latter case, Pine Research will issue an RMA for service.

3Rotating Ring-Disk Electrodes (RRDE)

3.1Electrical Test for AFE6M/AFE6MB Shaft

RRDE shafts are divided into three electrically-isolated sections (see Figure 1). Section A of the shaft connects to the rotator while sections B and C connect to the disk and ring, respectively. The resistance between these sections should be infinity. To test the shaft, use a multimeter to measure the resistance between the connections, as follows.

The resistance between A and B should be infinity
The resistance between B and C should be infinity
The resistance between A and C should be infinity

Rotating Ring Disk Shaft with Electrically Isolated Sections Labeled

Figure 1. RRDE Shaft with Electrically-Isolated Sections Labeled

3.2Electrical Test for Rotating Ring-Disk Electrode Tips (E6, E7, and E8 Series)

WARNING: Be extremely careful when making contact with the electrode surfaces so as not to damage them by scratching the electrodes with the multimeter probes.

The RRDE tip is detachable from the shaft. As such, there are electrical sections within the tip that enable the ring and disk electrode surfaces to electrically contact the shaft, yet remain isolated from each other. The disk electrode E is in electrical contact with the threaded pin D (see Figure 2). The ring electrode G is in electrical contact with the threaded end of the tip F (see Figure 2). Use a multimeter to measure the resistance between these connections, as follows.

The resistance between D and E should be less than 10 Ω
The resistance between F and G should be less than 10 Ω
The resistance between D and F should be infinity
The resistance between E and G should be infinity

Rotating Ring-Disk Electrode Tip with Electrical Connections Labeled

Figure 2. RRDE Tip with Electrical Connections Labeled

4Rotating Disk Electrodes (RDE)

4.1Electrical Test for AFE3M Shaft

The AFE3M shaft has two electrically-isolated sections, A and B (see Figure 3). Section A of the shaft connects to the rotator while section B connects to the disk. The resistance between these sections should be infinity. To test the shaft, use a multimeter to measure the resistance between the connections, as follows:

The resistance between A and B should be infinity

Rotating Disk Electrode Shaft with Isolated Electrical Connections Labeled

Figure 3. RDE Shaft with Isolated Electrical Connections Labeled

4.2Electrical Test for RDE Tips (E3, E5, E5TQ, and E6TQ Series)

There are two sizes of RDE tips available for purchase from Pine Research: 12 mm OD (E3 series) and 15 mm OD (E5, E5TQ, and E5TQPK series). For the 12 mm OD tip, the disk electrode E is electrically-coupled to the female threading D (see Figure 4a and Figure 4b). For the 15 mm OD tip, the disk electrode E is electrically-coupled to threaded pin D (see Figure 4c). The resistance between D and E of RDE tips should be fairly small. Use a multimeter to measure the resistance between these connections, as follows.

The resistance between D and E on the shaft should be less than 10 Ω
The resistance between D and E on the shaft should be less than 10 Ω

Rotating Disk Electrode with Electrical Isolation Labeled

Figure 4. a) Front and b) Back of a 12 mm OD RDE tip and c) a 15 mm OD RDE Tip Showing Electrical Isolation

INFO: Permanently-mounted electrode disks, such as found in E5 and E6 electrodes, may be in electrical contact with both D and F. In other words, section D is shorted to section F on the electrode tip. This may not be the case for tips purchased before 2015, where section D and F were electrically-isolated.

5Rotating Cylinder Electrodes (RCE)

Pine Research manufactures two different shafts to be used in conjunction with 15 mm and 12 mm cylinder inserts (part numbers AFE9MBA and AFE3M, respectively). The latter shaft, AFE3M, was discussed in section 4.1.

5.1Electrical Test for AFE9MBA Shaft

The AFE9MBA shaft has two electrically-isolated sections, A and B (see Figure 5). Section A of the shaft connects to the rotator while section B connects to the cylinder. The resistance between these sections should be infinity. To test the shaft, use a multimeter to measure the resistance between the connections, as follows:

The resistance between A and B should be infinity

Rotating Cylinder Electrode Shaft with Electrically Isolated Sections Labeled

Figure 5. RCE Shaft with Electrically-Isolated Sections Labeled

5.2Electrical Test for 15 mm RCE Tips (E9 Series)

The cylinder E slides directly onto the lower threaded of the shaft, coupled to section B (see Figure 6). Thus, the resistance between shaft section B and cylinder E should be minimal while the resistance between shaft section A and cylinder E should be infinity for the 15 mm OD RCE. Use a multimeter to measure the resistance between these sections as follows:

The resistance between A and E should be infinity
The resistance between B and E should be less than 10 Ω

Figure 6. Electrical Isolation Labeled with Cylinder Inserted on Shaft AFE9MBA

5.3Electrical Test for 12 mm RCE Tips (ACQC Series)

The 12 mm RCE tip is detachable from the AFE3M shaft. For the cylinder to make electrical connection to the AFE3M shaft, the threading D is electrically connected to cylinder E on the RCE tip. Use a multimeter to measure the resistance between these sections, as follows:

The resistance between D and E should be less than 10 Ω

Figure 7. RCE Shaft with Electrically-Isolated Sections Labeled

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