UL 9540: Construction Requirements

UL 9540 defines construction requirements to ensure ESS are built reliably to high safety standards. Construction requirements include:

Enclosures

• Must have strength and rigidity to resist physical abuses during transport, install, and intended use
• Required to be designed to prevent inadvertent access to hazardous parts and rated for intended water exposure

Electrical Protection

• Wiring installed must be insulated and spaced to prevent inadvertent short circuits or arc flashing
• Short circuit protection must be integral to the ESS and the output terminals must be able to withstand short circuit current

Large-scale Fire Testing

• Electrochemical ESS are required to be subjected to fire testing in accordance with UL 9540A
• UL 9540A is a testing methodology for extreme abuse conditions to evaluate the fire and explosion hazard characteristics of ESS
• Safety features and battery management system are not active during testing to evaluate extreme fire and explosion characteristics

Safety Analysis of Control Systems

• Components within the system must work compatibly to prevent hazardous conditions
• Controls must be verified for electromagnetic immunity

UL 9540: Electrical Testing

The following are some of the electrical tests required in UL 9540. They evaluate the ability to withstand various hazardous conditions.

Electrical Performance Testing

• Must demonstrate insulation integrity after high voltage is applied to the ESS input and output terminals
• Transient overvoltage conditions can’t result in breakdown or flashover conditions
• Non-current carrying conductive parts of an ESS must be properly grounded and bonded as determined by resistance measurements
• Rated insulation resistance must be above minimum established industry thresholds
• Can’t create hazardous conditions under specified abnormal or single-point failure conditions

Electromagnetic Immunity Testing

• ESS must withstand electromagnetic interference (EMI) for the following potential EMI conditions: radio-frequency electromagnetic fields, electrostatic discharges, surges, power-frequency magnetic fields, and more
• The system must operate as intended without malfunctioning or experiencing significant performance degradation

UL 9540: Mechanical, Environmental, and Manufacturing Testing

System level mechanical, environmental, and manufacturing tests are performed as part of UL 9540. Examples include the following:

Mechanical and Environmental Testing

• Demonstrates structural integrity of wall mounted fixtures by applying a downward force to the mounted ESS
• Water exposure can’t result in insulation breakdown or water on parts that could result in a hazard
• Salt fog exposure can’t result in damage that could lead to electrical shock or overheating
• ESS intended for seismic installations must be evaluated to safety standards that subject ESS to simulated seismic events

Manufacturing and Production Testing

• 100% of production units are tested for dielectric breakdown and verify grounding and bonding systems
• Production quality controls are required that ensure monitoring of safety and quality for supply chain and assembly processes