Grothe transformers "MADE IN GERMANY". Bell transformers are optimized for short-term use such as those at ringing, gongs, bells and door openers occur in the living area, Safety transformers for continuous use. Grothe bell and safety transformers are protected by a PTC, which switches off the transformer on the primary side in the event of a short circuit or overload. If the PTC is triggered by an overload or short circuit, the transformer should briefly, but at least for 1 minute, be switched off in order to make it voltage-free then be able to put it back into operation. All transformers meet the highest environmental protection requirements, are tested according to EN61558 and have a certification