–IN

–

+IN

+

–V

+V

LOAD

50mV SHUNT

DC SUPPLY

5-40Vdc

POWER

GROUND

(0Vdc)

LOAD CURRENT

J3 MUST BE INSTALLED

(FACTORY SETTING) FOR

5-40Vdc SUPPLIES

J1 AND J2 POSITIONS

DEPEND ON INPUT RANGE

DCA5-20PC-X-DC1-XX

SHUNT MUST

BE IN LOW SIDE

1

1

1

2

2

CAL

TB1

TB2

J1 J2

J3

1

1

2

2

3

1

2

1

1

1

2

2

CAL

TB1

TB2

J1 J2

J3

1

1

2

2

3

1

2

–IN

–

+IN

+

–V

+V

LOAD

50mV SHUNT

DC SUPPLY

36-75Vdc

POWER

GROUND

(0Vdc)

LOAD CURRENT

REMOVE J3

FOR 36-75Vdc

SUPPLIES

SHUNT MUST

BE IN LOW SIDE

DCA5-20PC-X-DC1-XX

TECHNICAL NOTES

Figure 2. Low-Side Shunt Connections for "-DC1"

5-40Vdc Non-Isolated Supply Models

To ensure safe and reliable operation, DCA5-20PC dc ammeters must

only be installed and serviced by qualified technical personnel. DC

ammeter applications can expose a user to potentially lethal currents and

voltages. Power and signal connections must be made with all associ-

ated power sources de-energized. Contact Murata Power Solutions if you

have any questions regarding the installation or operation of any of our

digital instruments.

1. Calibration: DCA5-20PC ammeters are designed to operate with 50mV

and 100mV dc shunts whose rated accuracy is ±0.25%, or better. The

output of less accurate shunts may fall outside the ammeter’s ±1% calibra-

tion adjustment range. Under normal indoor operating conditions, periodic

recalibration of DCA5-20PC ammeters is not necessary. The calibration

potentiometer, located on the back of the ammeter, is a ¾ turn type; do not

force its adjustment screw past the two end stops.

If user calibration is deemed necessary, it must be performed by qualified

personnel. Calibration is performed by applying a precision 50.00mVdc or

100mVdc (model specific, see ordering guide) signal to TB1, observing

correct polarity. Then, using an insulated slotted tool, adjust the calibration

potentiometer until the correct display reading is achieved. Contact MPS if

additional information is required regarding calibration or setup of DCA5-

20PC ammeters.

2. Wiring and Fusing: Power supply (TB2) and input (TB1) wiring must

be rated for the electrical and environmental conditions under which the

ammeters will be operated. They must also comply with any regulatory or

application-mandated requirements pertaining to the user’s installation. Con-

nections to DCA5-20PC ammeters must be made with all power sources

de-energized. Refer to the Functional Specifications section for TB1 and

TB2 wire gauge information.

DCA5-20PC ammeters’ shunt (TB1) and power supply inputs (TB2) are not

internally fused. Therefore, the supply wires connected to the meter and the

load should be fused according to the maximum current rating (or lower)

of the wire gauge used, in accordance with applicable regulatory codes.

Insulation should be stripped to within +/-10% of the stated dimensions. All

wires must be inserted into the terminal block openings such that the screw

terminal does not pinch any insulation. TB2 is to be used solely for power-

ing the meter’s internal circuitry; it must not be used to supply current to an

external load or auxiliary device.

3. Terminal Block Torque Ratings: It is important to tighten TB1’s and TB2’s

screw-terminals to their rated torque specifications of 3.6 pound-inches (0.4Nm).

Proper tightening will minimize losses and ensure reliable operation.

4. High-Side versus Low-Side Shunts: Incorrect shunt connections are

one of the most common problems encountered when applying digital

dc-ammeters. Incorrect shunt connections can cause permanent damage to

the ammeter and/or its associated equipment.

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 DCA5-20PC Series ammeters. Figures 2, 3, and 4

depict typical low-side shunt connections.

High-Side Shunts: ‘-DC4’ isolated-power ammeters 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 supply. Figures 5 and 6 depict typical high-side shunt connections. As

shown in Figure 6, isolated-power models can also be used in applications

Figure 3. Low-Side Shunt Connections for "-DC1" Models Modified for

36-75Vdc Non-Isolated Power (See Technical Note 5)

where one supply powers the ammeter and a second supply powers the

load, but the two supply grounds cannot be tied together. ‘-DC4’ isolated-

supply models include a built-in dc/dc converter to provide a minimum of

500Vdc isolation between the shunt (TB1) and power supply inputs (TB2).

5. 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 configured for 36 to 75Vdc operation by removing (opening) jumper

J3. Please note that this user modification can only be performed on ‘-DC1

power models. Also, all ‘-DC1’ models – including those that have been

modified for 36-75Vdc operation – can only be connected in low-side,

grounded-shunt applications. See Figure 3 for detailed wiring information.

www.murata-ps.com/support

DCA5-20PC Series

50mV & 100mV Input, LED-Display, Subminiature DC Ammeters

MPM_DCA5-20PC.C01 Page 3 of 6