Product Overview
Simpson 17751 Model 2154 4.5-Inch AC Ammeter 0-100A RMS
Condition
Unused new old stock (NOS). Rear housing marked 46695 with barrel label reading CAUTION USE ONLY WITH EXTERNAL TRANSFORMER. Includes rear mounting hardware with nuts and washers.
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Product Overview
Simpson Model 2154 (Catalog Number 17751) is a 4.5-inch Century Style analog panel meter configured for AC current monitoring across a 0 to 100 Ampere RMS scale. Built around a magnetically damped iron-vane movement, it accepts a standard 5A AC full-scale drive from an external 100:5 ratio current transformer. The black phenolic case features a glass window, knife-edge pointer, front-accessible mechanical zero adjuster, and heavy threaded brass terminal studs.
Key Features
- Scale range of 0 to 100 A.C. Amperes R.M.S. with primary scale increments every 20 amps
- Requires external 100:5 ratio current transformer (5A full-scale input movement)
- Classic Century Style 4.5-inch rectangular face with high-contrast white dial and black pointer
- Front mechanical zero-adjustment screw
- Dual threaded brass rear stud terminals for secure wiring lugs
- Four-corner rear stud mounting pattern for industrial control panels
- Molded housing marked Made in U.S.A.
Applications
- Industrial motor control centers requiring real-time primary line current monitoring
- Generator transfer switchboards and marine power distribution panels
- Custom benchtop AC load banks, variable transformer setups, and amateur radio linear amplifier supplies
- Vintage test equipment restorations requiring period-accurate Simpson Century series instrumentation
Frequently Asked Questions
Can this meter connect directly in line with a 100 amp load?
No. Connecting direct line current will damage the movement. The internal iron-vane mechanism accepts 0 to 5 amps AC and requires an external 100:5 ratio current transformer wired in line with the monitored conductor.
Does this meter include the required external current transformer?
Not included. A standard 100:5 AC current transformer must be sourced separately to match your wire gauge and busbar configuration.
What mounting configuration does this meter use?
The meter body mounts through a circular panel cutout and secures with four corner threaded studs, nuts, and washers.
How can this meter be distinguished from direct-reading ammeters in the same series?
Direct-reading models carry internal shunts or direct coils and lack transformer warnings, whereas Catalog 17751 features the factory red barrel label specifying use with an external transformer and operates on a 5A movement scaled 0-100.
An iconic American-made iron-vane meter with clean glass and sharp graphics, ready to drop into a restored switchboard or custom power rack. Built to outlive modern digital displays, it gives your electrical gear that reassuring, steady analog pulse.
