APPLICATIONS

PANEL INSTALLATION

Step 1.

Step 2.

Step 3.

Step 4.

8. Operation With 100mV Shunts: Many DCA5-20PC Series ammeters

can also operate with 100mV shunts. This is due to the fact that when

they are driven by a 100mV input, the display readings are double

those of a 50mV input. However, a 50mV shunt cannot be used in

a 100mV application because its maximum current rating will be

exceeded.

For our customer’s convenience, Murata Power Solutions offers a

series of 50mV and 100mV chassis-mount dc shunts that can be used

with DCA5-20PC ammeters. Part numbers for accessory shunts can

be found in the Ordering Information section. A data sheet describing

these shunts is available at www.murata-ps.com.

Table 1 indicates the obtainable readings of the seven DCA5-20PC

models that can be operated with 100mV shunts. Be sure to enable the

correct decimal point (see decimal point selection instructions).

9. Noisy Power Supplies: Some power supplies contain high-frequency

switching devices that may conduct and/or radiate significant noise

onto the low-level 50/100mV shunt signal. Even though the DCA5-

20PC incorporates built-in filtering at its shunt input, some portion of

this noise may be amplified and subsequently measured by the DCA5-

All connections and modifications must be made after the ammeter

is securely attached to the panel, with all load and supply voltages

de-energized (off).

The installed wire-positions should be such that minimal forces are applied

to TB1, TB2, and the ammeter itself. In high-vibration environments, the

use of wiring strain-reliefs is recommended.

To insure a secure panel-mount installation, MPS recommends using the

DMS-BZL4-C (with sealing gasket) bezel assembly supplied with each

20PC’s sensitive circuitry. The amplified noise introduces errors that are

particularly noticeable at zero load current (i.e., the ammeter may not

display a relatively steady “000” reading).

Connecting an external, unpolarized capacitor across TB1’s “+” and

“–” inputs, and/or across the shunt’s 50mV output terminals, can help

reduce noise-related display errors. In certain situations, the use of

twisted pair or shield wiring may be required. As a general rule, avoid

using excessively long leads between the ammeter and the shunt.

Figure 8. Panel Installation

ammeter. See the Mechanical Specifications section for detailed panel

cutout and ammeter dimensions.

Following the four-step sequence shown in Figure 8 below, being careful

not to apply excessive force or twisting motions, insert the ammeter into

the panel opening. When using the DMS-BZL4-C’s sealing gasket, make

sure it is positioned between the ammeter’s flange and the panel’s front

surface. Be sure to use and securely tighten all four screws supplied with

the bezel assembly.

Model

100mV Shunt Readings

DCA5-20PC-1

10.00A/100.0A/1000A

DCA5-20PC-2

1.999A/19.99A/199.9A/1999A

DCA5-20PC-3

60.0A/600A

DCA5-20PC-4

150.0A/1500A

DCA5-20PC-7

50.0A/500A

DCA5-20PC-8

800A

DCA5-20PC-9

1200A

Table 1. 100mV Shunt Readings

*

* With respective decimal point enabled

2

1

3

4

www.murata-ps.com/support

DCA5-20PC Series

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

MPM_DCA5-20PC.C01 Page 5 of 6