Siemens 3VM9988-0AB12 Low-voltage Industrial Auxiliary Function MCCB

The Siemens 3VM9988-0AB12 serves as a tripped signaling switch, commonly referred to as an auxiliary contact. Its core function is to provide a contact closure or opening that signals the operational status of the associated 3VM circuit breaker, specifically when the breaker has tripped due to an overload or short circuit. This remote indication is invaluable for monitoring systems, control panels, and alarm systems, allowing operators to quickly identify fault conditions without direct observat

While the 3VM9988-0AB12 is specifically designed and optimized for integration with Siemens 3VM series molded case circuit breakers, some accessories are designed to be compatible with multiple series within a manufacturer's product line. However, for guaranteed performance and safety, it is always recommended to verify compatibility with Siemens' official product documentation or with a Siemens technical representative. Using it with non-specified breakers may lead to improper function or safet

This accessory is widely applied in industrial automation, control cabinets, and switchgear assemblies. Its primary role is to transmit the tripped status of a circuit breaker to a remote location or a control system. This is crucial for applications such as supervisory control and data acquisition (SCADA) systems, alarm panels, or PLC (Programmable Logic Controller) inputs where immediate notification of a protective device actuation is required to prevent further damage or ensure operational c

The Siemens 3VM9988-0AB12 has a rated operational voltage of up to 240V AC or 250V DC and a thermal current limit of 6A. The operational current ratings vary depending on the load type and voltage, for instance, it can handle 6A at AC-12 and AC-15, and various lower amperages at DC-12 and DC-13. It's essential to ensure that the signaling circuit's voltage and current requirements fall within these specifications to guarantee reliable operation and prevent component failure.

Installation typically involves snapping the accessory onto the side of a compatible Siemens 3VM circuit breaker, occupying a 7mm module space. Wiring is done via screw-type terminals. Qualified personnel should first de-energize the system. The changeover contacts (1 C/O) mean there is a common terminal, a normally closed (NC) terminal, and a normally open (NO) terminal, allowing for flexible configuration in signaling circuits. Refer to the specific installation manual for precise wiring diagr