The acceptance test is also the last point at which a discrepancy is inexpensive to resolve. After shipment, a specification shortfall becomes a commercial discussion about who bears the cost of modification or replacement.

What an instrument FAT should verify

The test should verify that the delivered equipment meets the specification it was purchased against. That means the ranges, the accuracy at those ranges, the functions that were specified, the interfaces and export behaviour, and the contents of the delivered package.

Verifying against the specification requires the specification to be present at the test. Where the purchase was based on a datasheet rather than a written requirement, the datasheet is the baseline, and the acceptance test compares the delivered unit against the figures the purchase relied on.

The test should be recorded in a form that can be compared against the specification clause by clause. A narrative description of a successful demonstration does not allow that comparison and does not support a later claim that a specified function is absent.

Witnessing tests and acceptance criteria

The decision to witness or to accept a report should follow the consequence. Where a specification shortfall would be expensive to resolve after shipment, or where the test involves conditions that cannot be reproduced on site, witnessing is justified.

The acceptance criteria should be agreed before the test, derived from the specification. Each criterion should state the quantity, the required value and the tolerance, so that the result is a comparison rather than an opinion.

Where an independent verification of accuracy is performed, the reference used should itself be traceable and its own calibration status current. A verification performed against an uncalibrated reference demonstrates nothing. The practice framework for accepting delivered equipment is published by NETA and by the accreditation bodies such as ILAC and IAF.

Verification against the stated specification

The output capability row is the one most often tested in a way that proves nothing. A set can meet its voltage rating on a light load and fail to meet it on the load the buyer specified, and the acceptance test should use the specified load.

Calibration certificates and traceability

The calibration certificate supplied with the instrument should demonstrate an unbroken chain of comparisons to a national or international reference, with an uncertainty stated at each link. A certificate that reports results without identifying the reference does not demonstrate traceability.

The scope of the certificate should cover the ranges and conditions the instrument will be used under. A certificate covering a limited range, or issued under laboratory reference conditions only, does not support use outside those conditions, and the manufacturer’s temperature coefficient becomes the relevant figure.

The practical guidance on establishing and documenting traceability is described in the NIST handbooks, the reference framework for the units is published by BIPM, the requirements for legal metrology instruments are published by OIML, and the measurement system requirements that apply to high-voltage measuring equipment are set out in IEC 60060-2.

Software, firmware and reporting checks

The software supplied with modern test equipment is part of the deliverable, and its version should be recorded at acceptance. A version recorded at delivery becomes the reference for later updates and for any support discussion.

The reporting behaviour should be exercised, not assumed. Producing a report from a test, opening the exported data in the buyer’s own software and confirming that the conditions are included alongside the values are all checks that take minutes at the factory and can take weeks to resolve after delivery.

Where the equipment stores results internally, the storage capacity, the export route and the behaviour when storage is full are worth confirming. Where the equipment connects to a network, the addressing and the required services should be established at acceptance rather than discovered at the buyer’s site.

Packing, documentation and spares

The packing should suit the transport the equipment will actually travel by, and the transport configuration should be verified: the number of pieces, the weight of each and the lifting points. Equipment that has to be lifted by crane on site but is packed for a forklift has a mobilisation problem that will appear as site delay.

The documentation set should be checked against the specification: operating and service manuals, the languages and format specified, the accessory list with part numbers and the spares list with lead times. Checking the manuals at the factory avoids discovering that a language version was not supplied after the equipment has shipped.

The spares list deserves specific attention for the items that wear. The availability and lead time of consumables determine whether a planned outage can proceed, and confirming that at acceptance is easier than discovering it during a window.

Sign-off and punch list

The acceptance record should contain the specification clause, the requirement, the observed result and the verdict, signed by both parties. That structure makes the document usable in a later discussion about whether a function was delivered.

Items that do not meet the specification become a punch list with an owner, a corrective action and a date. Any item that affects the specified performance should be resolved before shipment; items that do not can be closed after delivery if they are recorded and accepted in writing.

The punch list should be attached to the purchase documentation rather than kept separately, so that the equipment arrives with its open items visible rather than remembered.

What to do when a FAT item fails

The first step is to establish whether the failure is in the equipment, in the test method or in the reference. A verification performed with an uncalibrated reference, or at a load the instrument was not specified for, produces a failure that describes the test rather than the equipment.

Where the failure is in the equipment, the options are correction before shipment, replacement, or acceptance with a documented deviation. The third option is legitimate provided the deviation is recorded, the consequence is understood and the price reflects it.

Where the failure reveals that the specification was ambiguous, the ambiguity should be resolved and recorded rather than resolved informally. A specification that was read two ways will be read two ways again at the next purchase, and the resolution belongs in the template. Support arrangements that form part of the delivered package, including calibration and spares, are described under testing services and OEM/ODM solutions, the instrument range the process applies to is listed under all electrical testing equipment, and the certification scope of individual product lines is shown on the certifications page.