Technical library

In some cases, measuring actual current on the primary conductor is not possible and the user may have to measure current on the secondary circuit of a CT. In this case, the MPQ can be programmed to display the actual primary current values instead of the current measured on the CT secondary circuit. This is done by following the steps given below.

Low voltage cable faults are often unstable, so they can only be located when the cable is conducting live voltage. Testing under these conditions is extremely hazardous, so separations filters, as well as constructional safety methods, should be employed at all times.

Low voltage networks are a huge national investment, under daily pressure to give out power for hours at a time to a plethora of electrical appliances. It is therefore essential that their cables and transformers are tested often to prevent outage. To effectively test the components in low voltage networks, it’s important to know the different types of systems within them and how they are structured.

Fault occurrences in medium voltage networks are usually covered by redundancy in the system which, with appropriate switching, usually ensures a relatively uninterrupted continuation of the supply for the customer. A lengthy wait until the fault can be corrected only results in the increased risk of a second failure in this area, creating a customer outage that cannot be restored by switching.

In branched low voltage networks, low-resistance faults, interruptions and large changes in impedance can only be located by comparing fault-free and defective cores.

The use of T-branches in low voltage networks makes the evaluation of TDR traces considerably more difficult. Only through comparative measurements of fault-free and defective wires can possible results be achieved. The test pulses of the Teleflex are partially reflected at the T-joint with a negative algebraic sign, while test pulses that continue are simultaneously reduced in amplitude. The amount of reflection depends on the impedance in the main line and the continuing line.

Overview of low voltage cable fault location test methods

There are multiple ways to find a cable fault in a low voltage network, but no one method works for all situations. It’s only by knowing the pros and cons of each method that you can determine the most effective one to use in any given scenario and pinpoint the fault in as little time as possible.

There are many different tests that can be performed on a battery string. The question often arises which one should be performed?

Megger’s SMRT Series of relay test sets has been engineered to offer a full range of testing solutions built around flexibility and customization. These test sets are ideally suited for testing today’s complex micro-processor relays as well as legacy electro-mechanical relays. The versatility of the SMRT Series is ideal for performing commissioning and periodic maintenance testing to help keep the power on.