UL 991:2000 Tests for Safety-Related Controls Employing Solid-State Devices

UL 991:2000 is a critical safety standard from Underwriters Laboratories (UL) that outlines specific testing requirements for safety-related controls incorporating solid-state devices. Designed to address the unique safety risks associated with solid-state technologies (e.g., semiconductors), the standard applies to a range of control devices—such as protective relays, temperature cutoffs, and current-limiting controls—used in industrial, commercial, and certain residential settings where device failure could result in fire, electric shock, or personal harm. Its primary goal is to establish uniform criteria for evaluating the reliability, operational safety, and fault tolerance of these controls, ensuring they perform as intended under both normal and adverse operating conditions.

Central to UL 991:2000 are rigorous tests targeting the core performance and safety of solid-state safety controls, including resistance to electrical stress (e.g., voltage spikes, short circuits), thermal stability under extreme temperatures, mechanical durability, and proper functioning of failure-mode protections. Beyond technical testing, the standard also provides guidance on product marking and documentation to facilitate correct installation and compliance. For manufacturers, adherence to UL 991:2000 demonstrates that their solid-state safety controls meet globally recognized safety benchmarks, supporting market access (especially in regions acknowledging UL certifications) and instilling confidence in end-users regarding the safety of integrated systems and equipment.

LISUN supplies the fully test solutions for the following UL 991:2000, please see the below excel table:

UL 991:2000 Clause and Subject	LISUN MODEL
11 Power Supply Voltage Dips and Short Interruption Test corrosion	CSS61000-11
12 Transient Overvoltage Test	SUG335
14.2&14.4 Electrical fast transient/burst test	EFT61000-4
14.8 Radiated EMI test	GTEM-2&EMI-9KC
15 Electrostatic Discharge Test	ESD61000-2
16 Composite Operational and Thermal Cycling Test	GDJS-015B
18 Thermal Cycling Test
19 Humidity Test
20 Dust Test	SC-015
21 Vibration Test	LVD-100KG