6. Glass Cartridge Fuse Replacement
1. Component Purpose
A multimeter’s current measurement path passes the measured current directly through the meter. If the user accidentally connects the meter across a voltage source while in current mode, a very large current flows through the meter.
The current measurement fuse protects the meter’s internal shunt resistor and circuitry from this fault current. A fast-blow fuse disconnects the path as quickly as possible to prevent internal damage.
Required: Glass Cartridge · 500mA (0.5A) · ≥250VAC · Fast Blow · 5mm × 20mm · Littelfuse · RoHS
2. How to Find It on DigiKey
Go to DigiKey.com → Circuit Protection → Fuses
Apply these filters:
- Fuse Type → Cartridge, Glass
- Current Rating (Amps) → 0.5A (500mA)
- Voltage Rating - AC → 250V or higher
- Response Time → Fast Blow
- Package / Case → 5mm x 20mm
- Manufacturer → Littelfuse Inc.
- Part Status → Active
Important: This is a direct replacement fuse. Current rating, response time, and physical size must match exactly. Do not substitute with a different current or a slow-blow type.
3. Key Specifications & What They Mean
| Specification | Required | Why |
|---|---|---|
| Fuse Type | Cartridge, Glass | Standard instrument-grade fuse body. |
| Current Rating | 0.5A (500mA) | Must match instrument manual exactly. |
| Voltage Rating | ≥250VAC | Meter may be used on mains circuits. |
| Response Time | Fast Blow | Quick disconnect to protect meter internals. |
| Size | 5mm × 20mm | Must fit existing fuse holder in the meter. |
| Manufacturer | Littelfuse | Company AVL requirement. |
| RoHS | Yes | Compliance required. |
4. Selecting a Safe, Production-Ready Part
The filtered list will show matching parts. Before you pick one, check: Is it Active? Is stock available? Is a datasheet available?
Full checklist: How to Select a Safe, Production-Ready Component — EWskills Guide