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Inspection, Reconditioning and Testing of Low Voltage and Medium Voltage Fuses, Non Refill and Refill Styles
I. Introduction
Fuses play a major roll in protection of electrical circuits, loads and operators. Fuses are used to protect against short circuit under extremely high currents, as well as overload. They are suitable for use in the protection of transformers, electric motors, magnetic and solid state control assemblies, and power distribution runs just to name some of their many applications in industry today.
As with most PEARL Standards, the PEARL low and medium voltage fuse standards and their testing parameters have been developed to prevent damaged fuses from re-entering the market place. Visual inspection of the exterior condition of the fuse, its containment barrel or its ferrule ends constitutes a major part of the standard but offers little insight into the internal condition of a fuse. Test parameters in use with manufacturers "returned product" inspection procedures focus on resistance values attainted through "cold resistance" testing. As with all PEARL standards, the use of OEM test value acceptance standards is always recommended.
PEARL Section 3100 reconditioning standards include:
II. Components
III. Testing and Inspection
This standard is designed to verify that a low voltage fuse or a medium voltage fuse is in a safe and reliable operating condition. In the event that the fuse is not in this condition then it must be discarded. The term "reconditioning" is defined for Section 3100 only as "the process of enhancing the physical attributes of a fuse that already has the proper electrical properties."
The purpose of this enhancement is twofold:
The PEARL Section 3100 Low Voltage and Medium Voltage Fuses, Refill and Non Refill Types standard continues with a "Recondition Evaluation," which is a detailed inspection of all parts of the low or medium voltage fuse, including but not limited to the components listed above.
Section I for PEARL Section 3100 Low Voltage and Medium Voltage Fuses, Refill and Non Refill Types, begins with identification of the test equipment necessary to complete the standard, including:
One of the following pieces of test equipment is required to perform the fuse linkage resistance testing requirements of this standard:
Section II Recondition Evaluation-Inspection and Testing identifies each component and assembly part that must be inspected to determine the components viability and scope of reconditioning required to bring the component back to original operating condition. Results and notes from the pre-reconditioning inspection and test are recorded in the PEARL Reconditioning Evaluation and Test forms that accompany each low and medium voltage fuses standard.
IV. Reconditioning
Assembly of the reconditioned components and subassemblies is followed by final inspection and testing. As with all testing, inspection, and reconditioning operations, final inspection and test results are recorded onto the Evaluation and Test forms included with the standard. If a PEARL certified technician follows the reconditioning standard, the low voltage and medium voltage fuses, refill and non refill types assembly is eligible for a Blue PEARL Reconditioned Quality Seal.
Links to the full reconditioning standards for low voltage and medium voltage fuses:
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Link to the full Standard Number 3110