DMR35-DCV Series

Precision DC Voltmeter

DMR35-DCV.A01.D0

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TECHNICAL NOTES

1. Calibration

The DMR35-DCV1 is 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 6mm (0.24”). All 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 of 3.5 lb.-in (0.4Nm). 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 (+VS, -VS) are protected against momentary overvoltage and reverse polarity conditions. Input

terminals +VIN and –VIN 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 to applicable safety and regulatory requirements for the system in which the DMR35 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 DMR35 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 ft.) is strongly

recommended. Also, in systems with noisy power supplies, connecting an external, non-polarized capacitor across the +VS and -VS inputs

can help reduce measurement errors. In certain situations, the use of twisted pair or shield wiring may be required.

5. Self-Diagnostics

On 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.