85C1 300A DC Analog Panel Ammeter – 0–300A Range, 75mV Shunt, 64×56mm

The 85C1-300A is an analog panel ammeter designed to measure direct current (DC) in the 0 to 300 ampere range. It belongs to the widely used 85C1 series of square-type analog meters, which are known for their compact 64 × 56 × 60 mm housing, clear transparent front window, and reliable magneto-electric measurement mechanism. The meter uses a moving-coil movement with a 90-degree pointer deflection, providing a direct visual reading of current on a printed scale.

Because the 300A full-scale current is far beyond the capacity of a direct-connected moving-coil meter, this model is a non-direct (external shunt) type. It must be used with a 75mV current shunt connected in parallel. The shunt carries the main load current and develops a small voltage drop of 75mV at rated current; the ammeter then measures this millivolt-level signal and displays the corresponding current value. The meter’s basic error is ±2.5% (accuracy class 2.5), which is standard for industrial panel meters of this type. The housing is designed for vertical panel installation, with a round cutout of approximately Φ50 mm (or Φ53 mm for the larger variant).

The 85C1-300A is a passive analog indicating instrument—it does not require an auxiliary power supply and does not include a digital display, communication interface, or data logging function. It is intended for industrial control panels, automation systems, automotive electrical monitoring, battery charging stations, and general DC power distribution where a robust, low-cost, and immediately readable current indication is required. The meter is compatible with standard 75mV shunts available in the market, and the shunt must be selected with a current rating equal to or greater than the maximum measured current.