Megger XA-12991 DC Clamp-On Probe 1000 A for TORKEL 900 Series

Megger XA-12991 Overview

Disconnecting a station battery from its load just to run a discharge test is often not an option. With the Megger XA-12991 clamped around a battery conductor, a Megger TORKEL 900 series unit measures the total current leaving the battery, including the current drawn by the connected equipment, and holds that total at the set value. Megger lists the XA-12991 as the “DC clamp-on probe, 1000 A” for measuring current in an external circuit.

Who the Megger XA-12991 is for

It suits battery maintenance teams who test substation, telecom or UPS batteries without taking them out of service, and anyone running a TORKEL 930, TORKEL 950 or TORKEL 910 together with TXL extra loads. Megger’s TORKEL 900 user guide says external current measurement must be used in both of those situations.

Other clamps and current accessories are in our current accessories category, and the complete TORKEL family is on the Megger brand page.

Megger XA-12991 Key Features

How the XA-12991 fits into a TORKEL test:

• Lets the TORKEL regulate the total battery current, so changes in the regular load are compensated and the discharge current stays constant
• 1000 A DC clamp-on design: no need to open the current path, unlike a shunt
• Connects to the TORKEL’s I EXT ≤ 1 V input; the TORKEL’s DC OUT socket provides 9 V for an external current clamp
• Megger’s TORKEL 900 support notes give 1 mV/A as the ratio to enter for its optional 1000 A DC clamp-on probe
• Can be applied at a battery terminal or at an inter-cell connector

Megger XA-12991 Applications

Where the probe earns its place:

• In-service capacity tests on battery banks that must keep supplying protection, telecom or UPS loads
• Multi-unit discharge tests where one TORKEL controls TXL extra loads and needs to see the total current
• Battery systems that are plus-grounded, minus-grounded or floating, all of which Megger says the TORKEL can test

Megger XA-12991 Set-Up Notes from the TORKEL User Guide

Megger’s TORKEL 900-series user guide gives these steps for external current measurement:

• In TEST > Settings, set “Current measurement” to External and enter the clamp ratio
• Activate the warning and stop limit functions so the battery is protected if the clamp misbehaves
• Connect the probe to I EXT ≤ 1 V; Megger notes the best results come with the probe cables twisted
• Place the probe so the current through the TORKEL itself is included in the measurement
• Zero the probe away from magnetic fields before the test, and fit fresh batteries if the clamp uses them

Megger also points out that internal current measurement regulates faster, so it is the better choice when the set current must be reached within a few seconds.

Megger XA-12991 FAQ

Questions about using the XA-12991 with a TORKEL:

• What ratio do I enter on the TORKEL? Megger’s TORKEL 900 support answer says to enter 1 mV/A when using its optional 1000 A DC clamp-on probe, with Current measurement set to External.
• Is the XA-12991 the same as the XA-12990? They are separate Megger part numbers. The TORKEL 900-series datasheet lists the XA-12991, while the XA-12990 appears in Megger’s TORKEL 840/860 documentation. Order by the part number your TORKEL documentation lists, and ask us if unsure.
• Do I need the clamp for a normal off-line discharge test? No. With the battery disconnected from its load, the TORKEL’s internal current measurement (up to 220 A on the 930/950, 110 A on the 910) is used and is faster to regulate.
• Can a shunt be used instead? Megger allows a current shunt, but it must be connected in series on the negative side of the battery and may not be used above 300 V DC. The clamp avoids opening the circuit.

Planning an in-service test with the Megger XA-12991? Talk to MME

Our team at MME (MOHAMMAD MAHDI Electronics Trading LLC), an authorized Megger representative in the UAE, can review your battery system and suggest whether the clamp, a set of sensing leads or extra TXL loads belong in the kit. Request a quotation from MME.