UL 991 Safety Testing of Controls Employing Solid-State Devices
UL 991 compliance testing evaluates controls that use solid-state devices. As an ISO-17025 accredited test lab, we realize the importance of safety testing of controls. Meeting the environmental UL 991 requirements can be complex. Keystone Compliance guides companies through the process.
Keystone’s engineers take a consultative approach throughout the entire test program. We are in constant communication throughout the entire test process. We also offer competitive pricing and volume discounts. Lastly, Keystone Compliance expedites comprehensive reports shortly after the completion of the test.
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Summary of UL 991 Safety Compliance Testing of Solid-State Devices
The UL 991 standard applies to controls that use solid-state devices. This standard test method identifies potential risks unique to the electronic nature of a control.
Additionally, the UL standard supplements applicable end-product or component standards. UL 991 is not intended to serve as a sole basis for finding risks of fire, shock, or injury to persons. The requirements below do not include controls covered by end-product standards in which an electronic control investigation is specified.
UL 991 Environmental Compliance Testing Procedures
Thermal Cycling Test
The UL 991 thermal cycling test is conducted for 10 cycles. The temperature variations are carried out between 0 and 49 C. The transfer time from one extreme to the other needs to be less than 5 minutes. After the cycles are run, the unit is stabilized at a normal ambient temperature before operation.
Humidity Test
A unit will perform its intended function after humidity exposers are conducted. 6 to 12 cycles are recommended. The minimum humidity is 20%. The Maximum humidity level is 90 or 95%. The upper-temperature severity is 40C. On the other hand, the stabilizing temperature is 20C.
The unit is shielded from dripping condensate and can not be operated. During the last 2 hours of exposure, the control is energized and inspected.
Dust Test
The UL 991 dust test circulates 1.5 ounces of cement per cubic foot in the chamber. This test is carried out for 5 minutes by means of a blower/suction unit. This is done to completely surround the sample in the chamber.
Vibration Test
The sinusoidal vibration test must result in the fixing points of the control moving in phase and in straight parallel lines. The unit to be tested is secured to a vibration generator by its normal operating means.
The vibration level is carried out at 5 g unless otherwise specified by the end-product standard.
Expert UL 991 Environmental Compliance Testing
Our team strives to give our customers more time and energy on product development instead of testing. Keystone has a full lab of test equipment which permits us to provide short lead times on scheduling. In addition to UL 991 testing, Keystone has a full scope of expertise including fungus, immersion, freeze-thaw, and sand and dust.
Have a question about the compliance and safety testing of controls? Contact us or call (724) 657-9940 and we will determine the best course of action.