DB950 sounds like a severe case. I have had a traffic accident nearby that knocked over a power pole. It also dropped 12 KV lines unto a 3 KV line. I lost one transformer, a UPS (small one, 1 KVA and a ground arrestor. This could have been worse without the protection. When intermittent problems on a line causes variations in input voltages, internal parts (power supplies, circuit boards, anything that has AC voltage applied to it, has to have its own built in protection or it doesn't get the Underwriters Labs seal. This however a one shot deal, once an has occurred and the circuit provide the needed protection, it is toast. It is sacrificial. If the device continues to work, that's good, but now it has no more protection. These surges can also cause any device to be "struck" and a gate may get stuck in one state. This could cause any fault.