Factory Acceptance Test (FAT) of an Industrial UPS: What Is Verified?
Updated: Aug 31
The Factory Acceptance Test (FAT) is a fundamental stage in the manufacturing process of an industrial UPS. Before delivery and installation at the customer's site, the system undergoes a series of checks and tests to verify compliance with technical specifications, project requirements, and expected performance.
For industrial and mission-critical applications, the FAT is much more than a simple test: it is an important opportunity to verify that the UPS is ready to operate under the conditions for which it was designed.
What Is a Factory Acceptance Test?
The Factory Acceptance Test (FAT) is a verification procedure carried out at the manufacturer's facility before the equipment is shipped to the customer.
The objective is to verify that the industrial UPS:
complies with the project documentation and specifications;
has been correctly assembled;
meets the specified electrical and functional requirements;
delivers the expected performance under different operating conditions;
includes the appropriate protection, control, and monitoring systems;
is ready for installation and commissioning.
The FAT is normally planned on the basis of a test procedure agreed upon with the customer and may involve the manufacturer, customer, EPC contractor, and, where required, third-party inspection companies or organizations.
Why Is the FAT Important for an Industrial UPS?
An industrial UPS is often used to supply critical loads, where a power interruption can have significant consequences for the plant.
Oil & Gas, Power Generation, Utilities, infrastructure, transportation, and other industrial processes may require power supply systems designed to ensure high levels of reliability and continuity.
For this reason, testing the UPS before shipment makes it possible to identify potential issues during the manufacturing stage and confirm that the solution meets the agreed requirements.
The FAT also gives the customer greater visibility into the final product and the results of the tests performed.
What Is Verified During a FAT?
The tests may vary depending on the type of UPS, its configuration, project specifications, and applicable standards.
In general, a FAT may include several categories of verification.
1. Visual and Mechanical Inspection
The first stage generally involves an inspection of the equipment.
Items that may be checked include:
enclosure and mechanical construction;
dimensions;
component arrangement;
device identification;
wiring;
terminal blocks;
connections;
nameplates and markings;
finishing quality;
component accessibility.
This stage verifies that the UPS construction is consistent with the approved drawings and documentation.
2. Electrical Tests
An important part of the FAT concerns the electrical characteristics of the UPS.
Depending on the configuration, the following may be verified:
input voltage;
output voltage;
current;
frequency;
polarity;
DC system operation;
rectifier performance;
inverter operation;
bypass operation;
battery operation or related circuits;
system performance under the specified operating conditions.
The tests are performed according to the procedures defined for the project and verify that the system meets the specified electrical requirements.
3. Protection Tests
An industrial UPS must be equipped with protection systems appropriate to the characteristics of the application.
During the FAT, functions associated with abnormal and protection conditions may therefore be tested.
Depending on the architecture, these may include:
overvoltage;
undervoltage;
overcurrent;
DC-side abnormal conditions;
inverter faults;
rectifier faults;
loss of the power source;
bypass conditions;
battery protection functions.
The objective is to verify that the system correctly detects the specified conditions and responds according to the defined control logic.
4. Alarm Verification
Another important aspect concerns local and remote alarms.
An industrial UPS must be able to report abnormal conditions to operators and supervisory systems.
During the FAT, the following may be verified:
local alarms;
indicators and status signals;
dry contacts;
digital signals;
events;
fault conditions;
interfaces to supervisory systems.
Proper alarm management enables operators to quickly identify potential anomalies and take action according to the defined procedures.
5. Control and Monitoring System Tests
Modern industrial UPS systems are not simply power conversion equipment.
They are integrated systems that must communicate with the plant's control infrastructure.
During the FAT, the following may therefore be verified:
control panel;
operator interface;
monitoring systems;
communication functions;
signals to SCADA;
specified communication protocols;
event management;
alarm logging.c
These tests are particularly important for projects where the UPS must be integrated into a broader automation or supervisory system.
6. Operating Mode Verification
An industrial UPS can operate under different conditions and in different operating modes.
The FAT may include tests designed to verify system behavior when switching between different operating modes.
Depending on the architecture, the following may be verified:
Normal Operation
The system operates with the primary power source available.
Battery Operation
The UPS supplies the load using the energy available from the battery.
Bypass Operation
The load is supplied through the bypass circuit according to the specified configuration.
Return to Normal Operation
The system returns to normal operation after the primary power source has been restored.
These tests verify the correct management of the operating transitions defined by the project.
7. DC Section Tests
For industrial UPS systems equipped with DC systems, testing the DC section can represent an important part of the FAT.
The following may be verified:
DC voltage;
charging current;
rectifier operation;
battery management;
DC alarms;
protection functions;
DC distribution;
parameter monitoring.
The DC section is particularly important in applications where the UPS must provide continuous power to control, protection, and automation systems.
8. Redundancy Tests
For systems designed with redundant configurations, the FAT may include specific tests to verify UPS behavior in the event that one of the redundant modules or components becomes unavailable.
The objective is to verify that the system continues to perform its intended function according to the designed architecture.
Redundancy can be particularly important for mission-critical applications, where power availability is a fundamental requirement.
9. Documentation Verification
The FAT does not concern the equipment alone.
Documentation is also an important part of the acceptance process.
Depending on the project, the following may be reviewed:
electrical drawings;
layouts;
datasheets;
manuals;
I/O lists;
alarm lists;
certificates;
test reports;
quality documentation;
operating and maintenance procedures.
The documentation must be consistent with the actual configuration of the equipment.
10. Recording of Test Results
During the FAT, test results are normally recorded in a dedicated document or test report.
For each test, the following information may be documented:
test performed;
test conditions;
measured values;
result;
observations, if any;
non-conformities, if any;
corrective actions.
At the end of the activities, the report becomes an important part of the verification and acceptance process.
FAT and SAT: What Is the Difference?
It is important to distinguish between the Factory Acceptance Test (FAT) and the Site Acceptance Test (SAT).
The FAT is carried out at the manufacturer's facility, before shipment.
The SAT is carried out at the installation site, after the equipment has arrived and been installed.
In simplified terms:
FAT → verification at the manufacturer's facility
SAT → verification at the customer's site
The two processes are complementary.
The FAT verifies the correct construction and operation of the equipment before shipment, while the SAT verifies the installation and system performance under actual site conditions.
How Is a FAT Prepared?
An effective FAT requires careful preparation.
Before testing begins, the following aspects should be clearly defined:
project technical specifications;
acceptance criteria;
test procedures;
required instrumentation;
test conditions;
responsibilities of the parties involved;
documentation to be produced.
Preparation is particularly important for complex projects, where the customer may require specific test procedures and detailed acceptance criteria.
FAT as Part of the Engineering Process
The Factory Acceptance Test should not be considered a stage separate from the design process.
Testing requirements should already be taken into account during solution development.
The design must therefore consider how the following will be verified:
performance;
protection functions;
communications;
alarms;
redundancy;
interfaces;
operating modes.
This approach makes it possible to reach the FAT stage with a solution structured to be tested according to clear and agreed criteria.
LEVER's Approach to Factory Acceptance Testing
For a manufacturer of power conversion systems intended for industrial and mission-critical applications, the FAT represents an important step in ensuring the quality of the solution.
LEVER develops industrial UPS systems, rectifiers, inverters, and DC systems for applications in Oil & Gas, Power Generation, Utilities, Data Centers, and other infrastructures where power supply reliability is essential.
The engineering approach also includes testing and verification activities, with tests defined according to the project's technical specifications and requirements.
A well-structured FAT makes it possible to verify not only the product itself, but the entire system: from power conversion to protection, monitoring, and communication functions.
Conclusions
The Factory Acceptance Test of an industrial UPS is a fundamental stage in verifying that the completed solution complies with project requirements and is ready for installation.
Mechanical inspections, electrical tests, protection tests, operating condition simulations, alarm verification, monitoring, and communication tests all contribute to providing a comprehensive assessment of the system.
For mission-critical applications, the FAT is therefore an important tool for quality control, performance verification, and risk reduction before delivery.
The quality of an industrial UPS depends not only on the technology used, but also on the ability to design, test, and verify every detail of the system.
Do You Have an Industrial UPS Project?
LEVER supports its customers from design through testing, developing customized Power Conversion solutions according to the specific requirements of each application.
Contact the LEVER team to discuss your project.
