UL 991 is currently in its 3rd edition (2004) and has had two revisions. These requirements apply to controls that employ solid-state devices and are intended for specified safety-related protective functions. These requirements are intended to supplement applicable end-product or component standards and are not intended to serve as the sole basis for investigating the risks of fire, electric shock, or injury to persons associated with a control. These standard includes overvoltage and undervoltage tests, power supply interruption test, transient Overvoltage Test, Ramp Voltage Tests, Electromagnetic Susceptibility Tests and Electrostatic Discharge Test, as well as many others. We offer solutions to a variety of immunity testing including over voltages and Electrostatic Discharge (ESD).