Specifications

TECHNICAL NOTES
Figure 4. High-Side Shunt Connections for "-DC4"
8-36Vdc Isolated-Power Models
Figure 5. Using "-DC4" Isolated-Power Models to Maintain Isolation
Between Two Power Supplies
Figure 6. Using "-DC4" Isolated-Power Models
in Low-Side Shunt Applications
Low-side shunts: Applications that employ a single power supply to
power both the load and the ammeter, and the external shunt is located
in the negative side of the supply (commonly referred to as “low side” or
“grounded shunt”) should use ‘-DC1’ non-isolated power DCA-20PC Series
ammeters. Figures 2 and 3 depict typical low-side shunt connections.
High-side shunts: ‘-DC4’ 8-36Vdc isolated-power models must be
used in all applications that employ a single power supply to power
both the load and the ammeter and the shunt is located in the high side
(positive terminal) of the power supply. Figures 4 and 5 depict typical
high-side shunt connections. As shown in Figure 5, ‘-DC4’ isolated-
power models can also be used in applications where one supply
powers the ammeter and a second supply powers the load, but the two
supply-grounds cannot be tied together. ‘-DC4’ models include a built-in
dc/dc converter to provide a minimum 500Vdc isolation between the
shunt (TB1) and power supply (TB2) inputs.
5. Replacing Analog Panel Meters: DCA-20PC ammeters can be used
as replacements for analog panel meters if a suitable dc voltage
is available for powering the ammeter. In retrofi t applications, it is
important to determine the shunt’s electrical confi guration (i.e., high or
low side). If any doubt exists as to the shunt’s location, use only ‘-DC4’
isolated-supply models. All rewiring must be performed with the load
and power supply de-energized.
6. Operation With 36 to 75Vdc Power: As shipped, all ‘-DC1’ models’
rated operating supply range is +5 to +40Vdc. However, ‘-DC1’
models can be user confi gured for 36 to 75Vdc operation by removing
(opening) jumper J3. Please note that this modifi cation can only be
performed on ‘-DC1’ power models. Also, all ‘-DC1’ models – including
those that have been modifi ed for 36-75Vdc operation – can only be
connected in low-side, grounded-shunt applications. See Figure 3 for
7. Decimal Points: DCA-20PC ammeters’ decimal points are factory con-
fi gured for the respective full-scale input range. However, the decimal
points serve as placeholders only, they have no affect on the ammeter’s
displayed accuracy or resolution.
CAL
1
1
2
3
TB2
1
2
TB1
–
–
+
+
–V
LOAD
TB2-1 AND TB2-2
ARE INTERNALLY
SHORTED
DCA-20PC-X-DC4-XX
SHUNT IS IN
HIGH SIDE
–SHUNT
+V
+V
LOAD CURRENT
+SHUNT
DC SUPPLY
8-36Vdc
CAL
1
1
2
3
TB2
1
2
TB1
–
–
+
+
–V
LOAD
DC SUPPLY
8-36Vdc
TB2-1 AND TB2-2
ARE INTERNALLY
SHORTED
DCA-20PC-X-DC4-XX
SHUNT IS IN
LOW SIDE
–SHUNT
+V
+V
LOAD CURRENT
+SHUNT
CAL
1
1
2
3
TB2
1
2
TB1
–
–
–
+
+
+
–V+V
LOAD
CURRENT
LOAD
DC SUPPLY #1
8-36Vdc
+SHUNT–SHUNT
TB2-1 AND TB2-2
ARE INTERNALLY
SHORTED
DCA-20PC-X-DC4-XX
DC SUPPLY
#2
SHUNT IS IN
HIGH SIDE
www.murata-ps.com/support
DCA-20PC Series
LED Display, Subminiature DC Ammeters
with Built-In Shunts
MPM_DCA-20PC.B07 Page 4 of 6