Mersen A50QS250-4 Semiconductor Fuse 250A 500V AC Bolt-On

Purpose and fit

This Mersen A50QS250-4 semiconductor fuse protects power semiconductors in industrial and commercial equipment rated up to 500 V AC or DC at 250 A. Its fast-acting, single-element design interrupts fault current quickly to limit let-through energy. The bolt-on body style suits panel or busbar mounting where a secure, non-rejection connection is required.

Build integration

The fiberglass body measures 4-3/8 in long by 1-1/2 in diameter and uses a bolt-on termination, so it fits into existing fuse blocks or custom buswork without clips. A 200 kA interrupt rating at 500 V AC and 87 kA at 500 V DC means the fuse can clear high prospective short-circuit currents without upstream coordination changes. CE, UL Recognized (Guide JFHR2, File 60314) and CSA Certified (LR12636) markings simplify compliance documentation.

Sustained-load behaviour

Under continuous rated current the single element runs at a stable temperature because the fiberglass body dissipates heat evenly. During prolonged overloads the fast-acting characteristic melts the element before semiconductor junctions reach destructive temperatures. The non-indicating construction means no visual flag or microswitch is fitted, so status monitoring must be provided externally if required.