Martel Electronics DPM970 User Manual

DPM 970

Digital AC Voltmeter Module

A 3 ½ digit LCD panel meter, featuring 19mm (0.75“) digit height and LED backlighting, the DPM 970 is a true RMS voltage and current meter with 500V a.c.

➁

(2kV )and 2mA full scale readings as standard. By changing the value of scaling resistors or adding a shunt, this module will measure most a.c. voltages and
currents. The DPM 970 features auto-zero and suppression of d.c. offset voltage. The digital hold function freezes the last displayed reading. Calibration is
achieved via two multi-turn potentiometers for offset and scale. Connection to the meter is via screw terminals. The module is housed in a robust carrier
which can be boltedinplace or panel mountedusingthe bezel, window andclips provided.

19mm (0.75“) Digit Height

Screw Terminal Connections

Digital Hold

500V a.c. (2kV ) Full Scale Reading

➁

Measures Voltage and Current

LED Backlighting

SCALING

The value of the three scaling resistors RA1, RA2 and RB may be
altered in order to change the full scalereading(F.S.R.)ofthe meter

- see table.
voltage/current, short circuit ACV and COM andadjust the ZERO
potentiometer.
CAL potentiometer.

Required F.S.R. RA2 RBRA1

200mV 0R 0R Open
2V 910k 100k
20V 1M 10k
200V 1M 1k
2kV (factory default) 464K 536K 100R
2mA (factory default) - - 100R
20mA - - 10R
200mA - - 1R
2A - - 0.1R
20A - - 0.01R

NOTE

➀
➁

➂
➃

Other scaling factors can be achieved via the correct selection of
RA1, RA2 and RB values.

To ensure that the meter reads "000" with zero input

The meter will need re-calibration by adjusting the

➀
➀
➀
➀

0R
0R
0R

➀ ➁

➂
➂
➂
➂

➂ ➃

Use inputs ACV and COM for measuring voltage.
For measuring voltages above 500V RMS, external scaling
resistors must be used.
Use inputs ACI and COM for measuring current.
We recommend the use of a current transformer when
measuring in excess of 10 Amps. Consult current transformer
manufacturer ’s dataforconnectionsand recommendations.

Stock Number

Standard Meter DPM 970

Specification Min. Typ. Max. Unit

Accuracy (overall error) * 0.5 1.5 % (±2 count)
Full scale reading ** 0 1999 V
Resolution 1 V
Sample rate 3 samples/sec
Operating temperature range 0 50 °C
Temperature s 200 ppm/°C

tability
Frequency range (input voltage) 15 15k Hz
Input impedance (2kV range) 1 M
DC Supply voltage 7.5 9 14 V d.c.
Supply current (Backlighting off) 1.5 mA d.c.
Supply current (Backlighting on) 50 mA d.c.

@ 5Vd.c.

* To ensure maximum accuracy, re-calibrate periodically.
** Maximum safe input voltage across the ACV and COM terminals is 500V .

If voltages to be measured exceed 500V , then fit scaling resistors

RMS

RMS

RMS

Ω

RMS

externally to the module.

DIMENSIONS

40.5 (1.59)

44.0 (1.73)

24.0 (0.94)

39.0 (1.54)

All dimensions in mm (inches)

76.0 (2.99)

72.5 (2.85)

51.0 (2.01)

61.5 (2.42)

51.0 (2.01)

71.5 (2.81)

24.0 (0.94)

Ø5.7

(0.22)

24.5 (0.96)

Ø3.0

(0.12)

a

b

c

d

a. 1.0 (0.04)
b. 2.0 (0.08)
c. 6.5 (0.26)
d. 11.5 (0.45)

51 (2.01)

24 (0.94)

Display in Test Mode

Panel cut-out 72 x 40 (2.83 x 1.57)
Maximum panel thickness 3mm (0.12).

TST

XDP

ALM

HLD

RB

RA2

RA1

ACV ACI COM COM V+ V- LP- LP+

WEBSITE: http://www.lascarelectronics.com/

REAR
VIEW

V+

DP1

DP2

CAL ZERO

DP3

LASCAR ELECTRONICS LTD.

MODULE HOUSE, WHITEPARISH,

TEL: [phone] FAX: [phone]

WILTSHIRE SP5 2SJ UK

E-mail: [e-mail]

PO Box 770, Londonderry, NH 03053 1-800-821-0023
www.martelcorp.com

LASCAR ELECTRONICS INC.

3750 West 26th Street,

TEL: [phone] FAX: [phone]

Erie, PA 16506 USA

E-mail: [e-mail]

LASCAR ELECTRONICS (HK) LIMITED

FLAT C, 5/FL., LUCKY FTY. bldg., 63-65 HUNG TO ROAD

KWUN TONG, KOWLOON, HONG KONG

TEL: [phone] FAX: [phone]

E-mail: [e-mail]

SCREW TERMINAL FUNCTIONS

ACV Alternating voltage measurement input, acceptsup to500Va.c. By changing the values ofscalingresistors RA1, RA2 and RB, other voltage and

COM Return line forvoltage measurementinput(ACV) or currentmeasurement (ACI)input.
COM Return line forvoltage measurementinput(ACV) or currentmeasurement (ACI)input.

LP+ Positivesupplyfor LED backlighting.

HLD Digital Hold option. Connect toV+to hold last displayed reading indefinitely.
ALM Alarm “!” annunciator.Connect to XDP to display.

XDP Annunciator drive wavefor m. Used to drive alar m annunciator (ALM) ifrequired.

current ranges can be achieved.Tomeasure in excess of 500V a.c., remove RA1, RA2 and RB from the meter and externally;linkRA1 and RA2 on
the meter. See scaling table for suitable valuesforRA1, RA2 and RB.

ACI Alternating current measurement input.

See Scaling table for suitable values for shunt resistor RB.

V+ Positivepowersupply input.

V- Negative power supply input.

LP- Negative supply for LED backlighting.

TST Connect to V+ to displayallsegments exceptdecimal points and annunciators.

It should not be operated for more than afewseconds as the DC voltage applied
to the LCD may “bur n” the display.This connection is normally at 5V below V+
and is the ground for the digital section ofthemeter.

V+ Auxilliary V+ for connections to decimal points DP1, DP2 or DP3.
DP1 199.9 Connect to V+ to display required decimal point.
DP2 19.99 Connect to V+ to display required decimal point.
DP3 1.999 Connect to V+ to display required decimal point.

SAFETY WARNING

Tocomply with the Low VoltageDirective (LVD93/68/EEC), input voltages to themodule’s connectors must not exceed500VRMS. If voltages to be measured
exceed 500VRMS, then fit scaling resistors externally to the module. If the mains power supply is connected to the module, then all the module’s connectors
must be considered to be floating at mains potential. Consequently due caution must be exercised when connecting to the module’s connector functions
under these conditions. The user must ensure that the incorporationof the DPM into the user’s equipment conforms tothe relevant sections of BS EN 61010
(Safety Requirements for Electrical Equipmentfor Measuring, Control andLaboratory Use).

APPLICATIONS

WARNING : Do not apply in excess of 500V a.c. to the meter.

Voltage

Current

Voltage

Current

Voltage

Current

V+

V-

V+

V-

V+

V-

V+

V-

V+

V-

V+

V-

+5V

-5V

+5V

-5V

+5V

-5V

110/240V

PSU 303

0V

110/240V

PSU 303

0V

110/240V

PSU 303

0V

Phase 1

Phase 2

Phase 3

Neutral

Load

Load

Load

ACV

COM

ACI

COM

ACV

COM

ACI

COM

ACV

COM

ACI

COM

3-Phase Current and Voltage

Measurement

Phase

Neutral

Phase

Neutral

Phase

LP+

V+

V-

LP-

Neutral

Powering the LED backlighting on a DPM 970

from the PSU 303's +5V and COM outputs.

Voltage

Load

ACV

COM

ACI

COM

Current

V+

V-

V+

V-

Single Phase Current and Voltage

Measurement

Load

ACI

CT

COM

V+

V-

Using a current transformer (CT) to

measure currents in excess of 10A a.c.

+5V

COM

-5V

+5V

-5V

+5V

-5V

110/240V

PSU 303

0V

110/240V

PSU 303

0V

110/240V

PSU 303

0V

Specifications liable to change without prior warning DPM 970 Issue 5 August/2002 M.C. Applies to DPM 970/4