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 | Accurate True RMS Reading
| Galvanic Isolation To 3.5 kv
| NEMA 4/IP65 Front Panel
| Unique Option POD Design
| Relay or 4-20mA Output Options
| RS485 Serial Modbus |
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TRUE RMS CURRENT AND VOLTMETER FOR AC
AND DC
DM3430 Series
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INTRODUCTION
The DM3430
is a true RMS current and voltage panel
meter suitable for measuring AC or DC signals. It has four
digit, high intensity LED display that can be set to show a fixed
number of decimal places with "auto-rounding" to always show
the maximum resolution.
It is highly accurate and designed to measure AC or DC voltages up
to 550 Volts or currents up to 6 Amps. Readings can be displayed
as current or voltage or, alternatively, the reading can be easily
scaled from the front panel to take into account a multiplier from a
transformed input or to display directly in engineering values.
The 3.5KV isolation gives added protection when the instrument is used
to measure high voltages. This is particularly important when
measuring current, in that the instrument can be mounted anywhere in
the measuring circuit and remains unaffected by any standing voltage.
The DM3430 has a number
of special software features including Peak and Valley memory (Storing
Maximum and Minimum readings) and an Alarm Inhibit that disables the
alarm function for a programmable period after start up. It is
available with a choice of two power supplies, S1 for 90-253 VAC, or
S2 for 20-35 VDC.
Output functions including dual relays, 4-20 mA retransmission or
Modbus RS485 serial communications. Options are all available
and easily installed without dismantling the case thanks to the unique
"plug and play" option pod design.
All programming is done via a simple to use menu accessible from
the instrument front panel or via the RS-485 Modbus RTU serial
communications option.
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TRUE
RMS EXAMPLE
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| The waveform shown is typical of that
encountered in line voltage measurement with a fundamental
plus 30% of 3rd harmonic. The 3430 will accurately measure
this waveform while a scaled average meter could produce an
error of 12%. |
BENEFITS OF TRUE RMS MEASUREMENT
The DM3430 uses true Root
Mean Square measurement. This RMS value is related to the
"heating effect" of a waveform i.e., the amount of heat that
a signal would generate in a resistor (1 VAC RMS would generate the
same amount of heat as 1 VDC). This is quite different to the
average or mean value of an AC signal, which is sometimes measured and
then scaled as an RMS value. This can be acceptable if the
waveform is a pure undistorted sine wave. Unfortunately this
rarely occurs in practice. Waveforms can vary considerably and
therefore very significant errors of up to 30% for different waveform
types can result as shown in the table below:
| Wave Type |
Crest Factor
(V Peak/V RMS) |
True RMS |
Mean Value
Calibrated to
read RMS |
% Error in
Mean Circuit 1 |
| .Pure Sine Wave |
1.41 |
0.707 |
0.707 |
0% |
.Symmetrical
.Square Wave |
1 |
1 |
1.11 |
+11% |
.Pure Triangle
.Wave |
1.73 |
0.577 |
0.555 |
-3.8% |
.SCR Waveforms
.50% Duty Cycle
.25% Duty Cycle |
2
4.7 |
0.495
0.212 |
0.354
0.15 |
-28%
-30% |
1 Error = (Mean Value + True RMS Value) / (True
RMS Value) * 100%
|
THE IMPORTANCE OF ISOLATION
The input is galvanically isolated to 3.5 KV from the rest of the
electronics circuitry. What this means in practice is that any standing voltages
can be ignored and currents or voltage differentials can be measured with high
levels of common mode potentials. The Common Mode Rejection Ratio is a measure
of the amount of error introduced when common mode voltages exist. The DM3430
has an exceptional rejection ratio of 102 dB which means that even high levels
of standing voltage have little or no effect on the overall measurement
accuracy.
SPECIFICATION @ 68 °F
| .INPUTS |
| |
.AC 1
|
.DC |
|
| .Ranges
2 |
.Voltage |
.550
.60 |
.±550
.±60 |
.Volts
.Volts |
| .Current |
.6 |
.±6 |
.Amps |
| .Accuracy 3 |
|
.0.1% Rdg ±0.1
FSD |
.0.1% |
.FSD |
| .Stability
4 |
|
.0.02 |
.0.02 |
.% / °C |
| .Input
Impedance |
.550 V Range
.60 V Range
.6 A Range |
.10
.1
.0.02 |
.1
.0.02
.0.02 |
.M ohm
.M ohm
.ohm |
| .Frequency
Range |
|
.0 to 20 |
.N/A |
.K Hz |
| .Frequency
Effect |
.20 Hz to 1 K
Hz
.1 K Hz to 20 K Hz |
.Negligible
.0.04 |
.N/A
.N/A |
.% / K Hz
.% / K Hz |
| .GENERAL |
| .Isolation
5 |
.3.5 |
.3.5 |
.K Volts |
| .Display
(with Auto-rounding) 6 |
.0 to 9999 |
.-999 to 9999 |
.Counts |
| .Resolution 7 |
.A/D
.Display |
.0.002
.0.017 |
.0.002
.+ve 0.017
.-ve 0.17 |
.% FSD
.% FSD
.% FSD |
| .Reading
Rate |
.3 |
.3 |
.Hz |
| .CMRR
8 |
.102 |
.102 |
.DB |
| .Power Supply |
.Switch Mode
S1
.Switch Mode S2 |
.90 to 252
.20 to 35 |
.90 to 252
.20 to 35 |
.VAC
.VDC |
NOTES:
1- Based on 50/60 Hz AC signal
2- All ranges have a 10% over-range capability
3- Crest factor is the ratio between the Peak voltage and the RMS
voltage and can have an effect on accuracy as shown in the following table:
| Crest Factor |
Degradation
of
Accuracy % |
| 1 |
0 |
| 2 |
0.5% |
| 3 |
2.5% |
4- Over ambient Range 32 to 140 °F
5- 3 way isolation between input, PSU and any outputs: IEC pollution
class 2
6- The A/D resolution frequency exceeds the display resolution.
Auto-rounding makes maximum use of the 4 digit display by reducing the
displayed resolution if the measured parameter exceeds the available digits
thus providing a level of performance in excess of the four digit capability,
i.e. if the reading id showing 999.9 and the input increases by 0.1 the new
reading will show 1000.
7- Perceived resolution increases with the level of filtering
8- Common Mode Rejection Ratio
ENVIRONMENTAL
| .Sealing to PANEL |
.NEMA 4, IP65 |
| .Ambient operating
range |
.-22
to +140 °F |
| .Ambient storage
temperature |
.-58
to +185 °F |
| .Ambient humidity
range |
.10 to 90% RH non
condensing |
APPROVALS
| .EMC |
.Emissions |
.BS EN 50081-1 |
| .Susceptibility |
.BS EN 50082-2 |
| .ELECTRICAL
SAFETY |
.BS EN 61010-1, UL
(pending) |
OUTPUT OPTIONS
Plug and Play Option Pods
Simple plug in pre-calibrated units, no dismantling or
calibration
..Pod-3000/02
Dual relay Alarm
..Two independent line rated relay
outputs (common connection) |
| .Contacts |
.2 x
Changeover relays common wiper |
| .Ratings |
.AC |
.DC |
| .Maximum
Load |
.5A @ 250 V |
.5A @ 30V |
| .Maximum
Power |
.1250 VA |
.150 Watts |
| .Maximum
Switching |
.253 Volts |
.125 Volts |
| .Electrical
Life |
.100,000
operations at rated load |
| .Mechanical
Life |
.50
million operations |
| .Termination |
| Standard... |
.5 way
tension clamp connector |
| Optional... |
.Screw
terminals |
| ..Pod-3000/03
Isolated re-transmission |
| .Ranges |
.0 to 10 mA (Active
or Passive) |
| .0 to 20 mA (Active
or Passive) |
| .4 to 20 mA (Active
or Passive) |
| .Minimum
current output |
.0 mA |
| .Maximum
current output |
.23 mA |
| .Accuracy |
.0.07% full scale |
| .Maximum
Output load |
| .Active... |
.1 K ohm |
| .Passive... |
.[(V supply - 2) /
20] K ohms |
| .Maximum
External Supply Voltage |
.30 V (Passive mode) |
| .Voltage
effect |
.0.2 µA/V |
| .Ripple
current |
.< 3 µA |
| .Isolation |
.500 VAC |
| .Stability |
.1 µA/°F |
| .Termination |
| Standard... |
.5 way tension clamp
connector |
| Optional... |
.Screw terminals |
COMMUNICATIONS
..Pod-3000/05
RS 485 Modbus Comms.
..PC communication for configuration
and monitoring. |
| .Physical
Layer |
.4 wire or 2 wire
half duplex RS485 |
| .Baud Rate
software selectable |
.19,200 or 9,600 |
| .Protocol |
.Modbus RTU format |
| .Isolation |
.500 VAC |
| .Maximum
Fan out |
.32
units |
| .Termination |
| Standard... |
.5 way tension clamp
connector |
| Optional... |
.Screw terminals |
| Optional... |
.Ribbon
Cable - RC |
SOFTWARE FEATURES
| .INPUT
MENU |
| .Type |
.550V,
60V, 6A |
| .Display
resolution |
.0, 1,
2 and 3 dps. (with Auto rounding) |
| .Scale |
.Scale
factor (Default 1) |
| .ACDC |
.AC or
DC input |
| .Filter |
.Off,
2 Sec, 10 Sec, Adaptive |
.OUTPUT
MENU (relay if fitted)
.The following parameters may be
set for each individual relay |
| .Alarm
type |
.Off,
High, Low, Test |
| .Setpoint |
.Setpoint
in engineering units |
| .Hysterisis |
.Alarm
Hysterisis in engineering units |
| .Alarm
delay |
.Off,
2 Sec, 5 Sec, 10 Sec, 20 Sec, 1 min, 2 min, 4 min |
| .Latch |
.Off,
On (latch reset from front panel) |
| .Invert
operation |
.Off,
On |
| OUTPUT MENU (Analog
Re-transmission if fitted) |
| .Span |
.4-20,
0-20, 0-10 (Set output range to 4-20, 0-20 or 0-10mA) |
| .Rt. Lo |
.User
Defined (Set low end of scale) |
| .Rt. Hi |
.User
Defined (Set high end of scale) |
| OUTPUT MENU (Modbus Comms if fitted) |
.Device
No.
.Baud Rate
.Connections |
.1 to
99
.19.2 Kb / 1.2 Kb
.2 wire / 4 wire |
| SYSTEM MENU |
| .List |
.Short
menu, Full menu |
| .Clear
enable |
.Off,
On |
| .Setpoint
enable |
.Off,
On |
| .Alarm
inhibit |
.Off,
2 Sec, 4 Sec, 10 Sec, 20 Sec, 1 min, 2 min, 4 min |
| .Passcode |
.4
digit passcode
(0000-Passcode disabled) |
| .Offset |
.User
calibration offset in engineering units |
Items in Italics
are only available if the "full menu" option has been selected
DOWNLOADS
DM3430 Instruction Manual (available soon)
DM3430 Literature
ORDER CODE
DM343(LED Option) / Power Option
| .DM343
Basic Model Number |
| .LED
Options |
.0 = RED LED version
.1 = GREEN LED version |
| .Power
Options |
.S1 = 90 to 253 VAC
50/60 Hz
.S2 = 20 to 35 VDC |
OPTIONS
| .Pod-3000/02 |
.Dual Relay
Output (2 per unit maximum) |
| .Pod-3000/03 |
.Isolated 4 to
20 mA re-transmission (1 per unit maximum) |
| .Pod-3000/05 |
.Isolated
Modbus RS485 (1 per unit maximum) |
| .Pod-3000/05-RC |
.Ribbon cable
option (Pod 3000/05 only) |
| .ACC001 |
.Pack of ten 5
way optional screw terminals |
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