The SITOP BUF1200 6EP4231-7HB00-0AX0 is a capacitor-based buffer module that bridges short power interruptions in 24VDC circuits without using batteries. With 1,200 joules (watt-seconds) of stored energy, it delivers 300ms of hold-up time at a full 40A load — enough to ride through the typical duration of a mains brownout, a fast bus transfer, or a generator start transient. At lighter loads the buffer time stretches proportionally: 2.4 seconds at 5A.

Why Capacitors Instead of Batteries

Unlike battery-based UPS modules, the BUF1200 needs no periodic replacement, no temperature-controlled charging, and no electrolyte monitoring. The internal capacitor bank charges automatically from the connected 24VDC supply and stands ready indefinitely. A green LED confirms the charged state. When input voltage sags, the module injects stored energy into the DC bus within microseconds — fast enough that downstream devices never see the dip. This makes it particularly suited for applications where battery logistics are impractical: remote substations, offshore equipment, and unmanned installations.

Universal Compatibility

The BUF1200 works with any standard 24VDC power supply, not just Siemens SITOP units. It connects in parallel with the DC bus using tool-free push-in terminals accepting 0.5-16mm² wire. Galvanic isolation separates input from output. Multiple BUF1200 modules can be connected in parallel for proportionally longer buffer times. The module occupies 70mm of DIN rail width and operates from -40°C to +85°C.

Key Decision Parameters

For hazardous-area installations requiring ATEX certification, see the 6EP4231-7HC00-0AX0 (BUF1200 Ex) variant.