A surge protector (or surge suppressor) is a device designed to protect electrical equipment from voltage spikes.
Surge protectors block or short to ground any unwanted voltages that pass a specific threshold. This limits the voltage that is allowed to pass through to connected equipment, devices or appliances.
Surge protectors are typically installed in distribution or control panels to protect connected industrial equipment. Their efficacy is determined by their peak voltage rating and response time. Heavy-duty protectors, for heavy machinery, are designed to dissipate thousands of Joules with rapid response times; smaller protectors can effectively protect control components and communications equipment at lighter loads.