DMS Accessories
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Murata Power Solutions Murata Power Solutions' 50mV and 100mV base-mounted current shunts are designed for measuring dc currents from 5A to 1200A. These precision shunts (+/—0.25% accuracy) connect directly to MPS's DCA5-20PC Series of dc ammeters. Installation is straightforward: simply connect the load circuit to the shunt's threaded studs and the shunt's mV Kelvin-outputs to the digital ammeter's input terminals. All models feature a rugged phenolic base that provides 750V isolation to the shunt's brass terminals, allowing for direct attachment to metal surfaces. A highly stable (+/-15ppm/°C) manganin sensing-element provides a wide -40 to +60°C operating temperature range. Please see the DCA5-20PC data sheet for additional ammeter-related information and detailed connection diagrams. Technical Notes IMPORTANT! To ensure safe and reliable operation, dc shunts and all associated equipment must be installed and serviced by qualified technical personnel. Never make any connections to the shunt, the load, or the ammeter with energized power sources. Contact Murata Power Solutions if you have any questions regarding the installation or operation of any of our instruments and accessories. 1. Base-Mounted Shunt Precautions: DC current shunts are low value resistors that develop a mV output when current passes through their highly-stable manganin resistive element. Under high current, continuous use operation, dc shunts will dissipate considerable power and may undergo a significant temperature rise. For example, if allowed to operate continuously at its full rated load, a 500A/50mV shunt dissipates 25 Watts (500A x 0.050V = 25 Watts). Therefore, whenever possible, be sure to specify 50mV shunts due to their inherently lower power dissipation and voltage drop. To ensure that the manganin sensing element does not exceed 125°C under worst case operating conditions, please read and follow the guidelines in the mounting and derating sections of this data sheet. Tighten all connections on the shunt per the torque specifications given in the mechanical dimensions and selection guide on page 3. Please note, the user is responsible for selecting the correct wire sizes (gauge) and wire type for the given application. 2. Mounting Considerations: All shunts should be mounted with their resistance blades in a vertical position to allow for natural convection cooling (see Figure 1). Forced-air cooling must be provided when vertical mounting is impractical, or in installations where the shunt is installed in a confined location. The shunt's manganin blades must never be allowed to exceed +125°C; doing so will cause permanent damage to the shunt. Shunts must be installed in a manner that protects them from damage due to thermal expansion forces produced by high- or short-circuit currents. In most cases, shunts are weaker than their external-circuit connections, so provisions for additional wiring-flexibility may be required in high current and/or high-vibration applications. Whenever practical, all shunts should be connected in the grounded side (normally the ‘chassis') of the dc supply. However, these shunts must be connected in the grounded side of the circuit when the dc supply exceeds 750 volts (the rated limit for the shunt's phenolic insulating base). When more than one wire is to be connected to each end of a shunt, the wires must be evenly distributed between both terminals (see Figure 1). Mount shunt on a vertical surface LOAD CURRENT Figure 1. Typical installation www.murata-ps.com/support MPM_DMS Accessories.D01 Page 1 of 4

3. Lead Extensions: The shunt's Kelvin outputs (i.e., their 50mV or 100mV output signal) should not exceed 24 inches in length (61cm), assuming 22AWG (0.5mm2) wire is used. If longer leads are necessary, the additional voltage drops in the leads must be taken into consideration as they will degrade accuracy and stability. However, MPS's DCA5 series dc ammeters feature a calibration potentiometer that can be used to compensate for some additional losses when long leads are employed; contact MPS for calibration information. 4. Continuous-Operation Derating: If continuous operation is...

DMS Accessories50mV and 100mV Base-mounted DC Shunts MECHANICAL SPECIFICATIONS 8-32 Kelvin output screws (all shunts): 14-15 in-lbs (1.58-1.69Nm) 8-32 Kelvin output screws (all shunts): 14-15 in-lbs (1.58-1.69Nm) www.murata-ps.com/support MPM_DMS Accessories.D01 Page 3 of 4

DMS Accessories50mV and 100mV Base-mounted DC Shunts MECHANICAL SPECIFICATIONS (continued) 8-32 Kelvin output screws (all shunts): 14-15 in-lbs (1.58-1.69Nm) Murata Power Solutions, Inc. 11 Cabot Boulevard, Mansfield, MA 02048-1151 U.S.A. ISO 9001 and 14001 REGISTERED This product is subject to the following operating requirements and the Life and Safety Critical Application Sales Policy: Refer to: http://www.murata-ps.com/requirements/ Murata Power Solutions, Inc. makes no representation that the use of its products in the circuits described herein, or the use of other technical...