Test Leads
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7. Test Leads
The RT3-100 does not require calibrated leads, so you may repair damaged leads. You may
also keep different sets of leads on hand for various applications.
Because of the high drive capability of the unit, you may use small, easy-to-handle current
leads. The standard 20 foot leads are #4 AWG flexible welding cable. For optimum battery
usage, total current lead resistance should be between 12 to 22 milliohms.
The Potential leads can be practically any length or gauge wire; the only requirement is that a
braided shield wire be used. When repairing Potential leads, it is important that the shield not
touch the test clip.
7.1. Types of Leads
Kelvin Clip Cables
- Kelvin clip cables employ only two clips, with one current lead and one
sense lead connected to each clip. When connected in this manner, test current flows through
the entire shunt, the sense leads are positioned exactly at the calibration points, and the small
resistance between the screw head and the load is in series with the high input impedance of
the meter circuit, thus being totally insignificant in its effect on reading accuracy.
Kantwist/Mueller Cables
- The Kantwist/Mueller test cable is arranged with four separate
attachments, with two heavy-duty clamps for the current leads and two smaller clips for the
sense leads. When using this cable, connect the sense leads to the calibration points and
connect the current leads so the test current passes both calibration points as it flows through
the load.
Spiked Probe Cables
- Spike probes speed up the taking of repetitive readings. Some spiked
probes have a read button, making use of the instrument a fast, one person operation. Spiked
probe cables have two current and two sense leads, but the sense leads are terminated with
probes rather than clips. To use these cables, connect the current leads across the load in the
same manner as the Kantwist/Mueller cables, and connect the probes to the calibration points.