|
TRUE RMS CURRENT AND VOLTMETER FOR AC
AND DC
DM3430 Series
|
- 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
|
|
|
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.
|
TRUE
RMS EXAMPLE
|
|
|
| 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 mounting. |
| .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
DM3430 Instruction Manual (available soon)
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 |
Call (713) 861-1100 for literature and pricing.
If you prefer to ask for information via the internet, email
info@sandelius.com.
© 2001 Sandelius Instruments, Inc.
- All Rights Reserved
|
