If you ask a variety of SPD Manufacturers the primary reason for unit failure, they should tell you that the answer is Temporary Over Voltage events (TOV’s).
Most, if not all, SPD manufacturers use Metal Oxide Varistors (MOVs) as the primary workhorse in their products. MOV’s are designed to help mitigate high speed transients that typically last no longer than a few milliseconds and cannot handle long term energy.
TOV’s are slow 60hz durational events with voltages up to 2 times nominal, lasting beyond a ½ cycle and up to many seconds. In general terms, TOV’s are a product of the utility grid itself via switching operations or faults and represent a real-world problem, not only for downstream equipment but for SPD’s as well.
PQ Protection SPD’s do not try and mitigate TOV events, which can result in a fail. Instead, they focus on what they were intended for - mitigating high speed transients.
Let us not forget, the purpose of an SPD is to increase reliability of “mission critical systems”, therefore the SPD itself must be exponentially more reliable than the system it is trying to protect.
PQ Protection SPD’s utilize Ultra2X technology. This technology prevents SPD failures from TOV’s by disabling reactions to a TOV event. It has been specifically designed to meet and exceed the safety requirements for the abnormal over-voltage testing of UL 1449 Edition 4.
Furthermore, many SPD’s permanently disconnect all protection from the circuit during an over-voltage or swell event, as defined by IEEE 1159 - an increase in the RMS voltage level to 110% - 180% of nominal.
Ultra2X technology allows the SPD to experience an abnormal over-voltage or swell up to twice its nominal operating voltage and still remain operational during and after this event. However, our technology allows the SPD to provide reliable and continuous protection to your sensitive electronic equipment.
PQ Protection is recommended for all sites, especially ones where sustained over-voltages are known to occur and where failure of traditional SPD technologies cannot be tolerated.