3020-01097-0 Datasheet, PDF (1/4 Pages) C&D Technologies – 50mV and 100mV Base-Mounted DC Shunts

DMS Accessories
50mV and 100mV Base-Mounted DC Shunts
DATEL’s 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 DATEL’s
DCA5-20PC Series of dc ammeters. Installation is straightfor-
ward: 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 operat-
ing temperature range. Please see the DCA5-20PC data sheet
for additional ammeter-related information and detailed connec-
tion diagrams.
General Specifications (All Models)
Rated Accuracy
±0.25% max.
Sensing Element
Manganin
Terminal Posts/Screws
Brass
Tightening Torgue
See Mechanical Dimensions
Current Rating
See Selection Guide
Operating Temperature
–40 to + 60°C (–40 to +137°F)
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 DATEL if you have any questions regarding the installa-
tion 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, continu-
ous 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 dis-
sipates 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.
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 cur-
rents. In most cases, shunts are weaker than their external-circuit con-
nections, 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 insu-
lating 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).
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 consider-
ation as they will degrade accuracy and stability. However, DATEL’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 DATEL for calibration information.
Mount shunt on a vertical surface
50A
50mV
LOAD
CURRENT
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.
50mV
OUTPUT
Figure 1. Typical installation
DIGITAL PANEL METERS
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