DMR35-ACA.A01.D0

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DMR35-ACA/mA Series

AC Ammeter

www.murata-ps.com

TECHNICAL NOTES

1. Calibration

DMR35 digital panel meters are calibrated at the factory at the time of manufacture. There are no user or field-adjustable calibration

features.

2. Wiring

Power supply and input wiring must be rated for the electrical and environmental conditions under which the meter will be operated. They

must also comply with any regulatory or application-mandated requirements pertaining to the user’s installation. The terminal blocks can

accommodate wire gauges ranging from #14 to #24 AWG. Wiring insulation should be stripped to the proper length as described in the

Terminal Block specifications table and wires must be inserted into the terminal block openings such that the screw terminal does not pinch

any insulation. It is important to tighten all screw terminals to their torque specification, which also may be found in the Terminal Block

specifications table. Proper tightening will help ensure reliable operation. Applications subject to vibration should use stranded wire. After

final assembly, inspect all terminal block connections for shorts between adjacent conductors; this step is especially important when using

stranded wire.

3. Protection and Fusing

DMR35 meters’ power supply leads (PWRA, PWRB) are protected against momentary overvoltage and reverse polarity conditions. Input

terminals INA and INB are protected against noise and brief transients. Protection, however, is not provided against sustained conditions

exceeding the limits listed in in the Performance & Functional Specifications Table. External fusing must be supplied by the user in

accordance with applicable safety and regulatory requirements for the system in which the meter is installed.

4. Noisy Power Supplies

Some power supplies contain high-frequency switching devices that may conduct and/or radiate significant noise onto the low-level signal

developed across the measurement inputs. Even though the meter incorporates built-in input filtering, some portion of this noise may be

amplified and subsequently measured by its sensitive input circuitry. Limiting runs of wire to less than 3 meters (10 feet) is strongly

recommended. In certain situations, the use of twisted pair or shield wiring may be required.

5. Self-Diagnostics

Upon power-on the meter performs a self-test and checks the integrity of calibration data stored in internal non-volatile memory. If the

factory calibration data has been corrupted, the meter will display ‘CAL’ on power-on and approximately once a minute thereafter to indicate

that the meter is relying on default calibration factors and that displayed measurements may have more than the datasheet-specified amount

of error. If the meter detects other internal fault conditions, it will attempt to reset itself. Repeated restarts, which appear in the form of a

highly intermittent display, are indicative of a hardware fault that cannot be cleared through a reset operation, in which case the meter should

no longer be used.