RSN Series – Riedon™ DC Ammeter Shunts / Busbar Shunts by Bourns

REV. 07/24

Specifications are subject to change without notice.

Users should verify actual device performance in their specific applications.

The products described herein and this document are subject to specific legal disclaimers as set forth on the last page of this document, and at www.bourns.com/docs/legal/disclaimer.pdf.

Technical Notes

Mounting: Shunts should be mounted with manganin resistive blades in a vertical position in order to promote the free convectional

flow of air. If vertical mounting is not practical, forced air cooling or adding heat sinks to the blocks can reduce the operating

temperature. The manganin blades must never exceed +140 °C, otherwise permanent resistance change may occur.

When current of 100 A or greater is passing through the shunt, the major portion of heat generated is dissipated by conduction

through the shunt terminal blocks into the connecting buss bar or cable. Therefore, it is necessary to ensure that good contact is made

between the shunt terminal blocks and the conductor terminals and that the conductors have adequate cross section to keep the

temperature of the shunt from exceeding 140 °C (125 °C recommended).

If the shunt is mounted in an enclosure, care must be taken to ensure adequate cooling. If the power density is greater than 1/4 watt

per square inch of the enclosure surface for all enclosed devices, additional cooling must be supplied in the form of air vents or fans.

Shunts also must be installed in a way that protects them from thermal expansion forces produced from buss bar or short-circuit

forces. Flexible wiring may be required in high pulse current, high vibration, or high temperature applications.

Where possible, all shunts should be mounted on the ground side of the circuit. For circuits above 750 VDC, RS shunts must be

mounted on the ground side due to the dielectric strength of the shunt base.

Operating Current Derating: For continuous operation, it is recommended that shunts are not operated at more than two thirds (2/3)

the rated current under normal conditions per IEEE standards for DC instrument shunts. At ambient temperatures above 40 °C, the

current must be further derated to prevent damage.

Pulse Operation: Shunts that do not need continuous operation and are only exposed to intermittent pulses can be operated at levels

above their rated current for short periods of times. Pulses are limited to the maximum temperature of the blades not exceeding 140 °C

(125 °C recommended). Many variables such as ambient temperature, cross section of the current carrying conductors, and pulse

duration make calculating exact values difficult. Shunt size will need to be validated by customer for pulse current and duty cycle on a

case-by-case basis.

CURRENT

CURRENT

UP

OUTPUT VOLTAGE

MOUNTING ORIENTATION

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