Product Overview
Empro 500A 100mV Bolt-Down Current Shunt - Stamped Brass Blocks, Blade Stack, Used
Condition
Used and clean, in very good condition. The two brass end blocks are bright with their original machining lines still visible, carrying light scratches and a few faint scribe marks from handling. One block is stamped 500AMP over 100MV on one face and A 500 100 on its reverse; the other block carries a small script maker's mark set inside a shunt-symbol cartouche on one face and a separate stamped 280 on its reverse. The flat alloy blades between the blocks show even brown-grey oxidation with one darker patch near the right block, normal for a shunt of this age. Both slotted sense screws are present and both bolt holes are clean and unthreaded of debris. Sold as a used part with no calibration certificate.
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Product Overview
The Empro HA-500-100 is a bolt-down DC current shunt that turns a 500 amp load current into a 100 millivolt signal an ordinary meter can read, which works out to a resistance of 0.0002 ohms. The construction is the classic four-terminal arrangement you can see in the photos: a stack of flat resistance blades brazed between two solid brass blocks, each block drilled through for the main current bolt and fitted with its own small slotted screw for the voltage sense leads. Against the PartsMine ruler the piece measures approximately 160 mm end to end. Markings are struck directly into the brass rather than printed on a label, so the rating stays legible for the life of the part.
Key Features
- Rated current: 500 A
- Output at rated current: 100 mV
- Resistance: 0.0002 ohms
- Markings stamped in the brass: 500AMP, 100MV, A 500 100, and 280
- Maker's script mark stamped inside a shunt-symbol cartouche on one block
- Four-terminal construction: through-drilled brass blocks for the load bolts, slotted screw terminals for the sense leads
- Resistance element is a stack of flat alloy blades brazed between the blocks
- Overall length approximately 160 mm against the ruler
- Condition: Used
Applications
- Electrician wiring a 500 A panel ammeter that expects a 100 mV full-scale input
- Battery shop running discharge and load tests where clamp meters run out of range
- Instrumentation technician feeding a data acquisition input that reads low-level DC millivolts
- Shop building a bench load bank and needing a current sense element that bolts to bus bar
Frequently Asked Questions
What does this shunt output, and at what current?
100 mV at its full rated 500 A, which is the 100MV and 500AMP stamped into the brass. That is 0.0002 ohms, so the reading scales linearly: 250 A gives roughly 50 mV.
How is it wired?
As the photos show, this is a four-terminal shunt. The load current passes through the two large drilled holes in the brass blocks, bolted to cable lugs or bus bar. The meter or DAQ input connects to the two small slotted screws, one on each block, so meter lead resistance does not corrupt the reading. Use your instrument's own wiring instructions for polarity and lead sizing.
Has it been tested or calibrated here?
No. It ships as a used part in very good condition with no calibration certificate and no test data. If your application needs certified accuracy, check the millivolt drop against a known reference before you trust the number.
What is the 280 stamped on the other block?
Unidentified. It is struck into the second brass block, on the face opposite the maker's cartouche, and reads as a shop or batch code rather than part identification. The rating stamps and the part number stamp are the marks to go by.
Why buy this used shunt instead of a cheap new one or a mystery auction lot?
Because you can see exactly what you are getting before you spend anything. There is one of these on the shelf, photographed from every side with its stampings readable, and it is sold as-is: used, uncalibrated, with the handling marks and blade oxidation shown in the pictures rather than hidden. What you take on is verifying the drop yourself; what you avoid is a crate of unmarked shunts with no ratings you can read. This item clears our free-shipping line on its own, and orders leave the Idaho warehouse the same or next business day.
Brass blocks, a stack of blades, and four numbers punched into metal that will outlast every label ever printed. Bolt it into the circuit and let it do the one job it has done since somebody first struck 500AMP into that face.
