external power supply 110-240V AC accessory for: TD500 Testing and commissioning devices for 3VA molded-case circuit breakers. The TD300 activation and trip box is a mobile, battery-operated local test device. One of its functions is to provide a temporary power supply to the Electronic Trip Units (ETUs) so that they can be operated and parameterized. It is also used to test the tripping function of the molded case circuit breaker. The TD500 mobile test device allows the proper functioning and connections of all connected system components to be tested at the breaker commissioning stage because it is capable of simulating every conceivable cause of breaker tripping. The molded-case circuit breaker behaves as it would in the case of a real trip event. Key features of these accessory components: 1. ETU series 5 and 8 power supply to activate the display. 2. Direct adjustment of parameter settings on ETUs from series 5 and 8. 3. Check for mechanical tripping functions (series 3, 5 and 8 ETU). 4. Check for tripping function L, S, I ,N, G (series 3, 5 and 8 ETU). www.siemens.de/3VA. Siemens offers a comprehensive portfolio of protection, switching, measuring and monitoring devices, distribution systems as well as switches and sockets for safe and efficient electrical infrastructure in buildings and industry.