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Laurel Electronics provides
digital panel meters / controllers, totalizers, counters, loop-powered meters,
temperature meters, for all types of transducers or process indication &
control. |
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Laureate™ True AC RMS Voltage
& Current Panel Meters
0.2
V - 660 V & 2 mA - 5 A full-scale ranges |
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Features |
| 0.2,
2, 20, 200 & 660 V ranges |
2,
20, 200 mA & 5 A ranges |
| 4
1/2 digit resolution |
99.9%
accuracy of full scale |
| AC
coupled input |
Crest
factor of 2.4 at full scale |
| Priced
competitively with less capable averaging AC meters |
Scalable
for direct readout of external current shunts or
current transformers |
| Peak
value display |
85-264
Vac and 90-370 Vdc power standard |
| Green
or red display |
NEMA
4X, 1/8 DIN case |
| Optional
dual relays, 4-20 mA & 0-10 V analog output,
RS-232/485 I/O, parallel BCD output, low voltage AC
& DC power. |
Certified
to UL 3101-1, CAN/CSA-C22.2, EN 61010-1 (CE Mark).
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to Order RMS Voltage & Current Panel Meter
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Description |
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The
Laureate™ True AC RMS digital panel meter offers a
high accuracy 4 1/2 digit display for five voltage
ranges and four current ranges. It is suited for AC
applications where there is considerable distortion
of current waveforms from nonlinear loading. The
input is AC coupled to read only the AC component,
such as ripple on a power supply.
The True
RMS AC digital panel meters use precision circuitry
to compute the root-mean-square of complex waveforms
from 10 Hz to 10 kHz. Spikes up to 2.4 times the
maximum of each range are accurately measured. This
provides a crest factor (Vp / Vrms) of 240 for a
signal amplitude of 1% of full scale, decreasing to
2.4 at 100% of full scale. |
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to Order RMS Voltage & Current Panel Meter
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High
common mode rejection allows stable readings with
current shunts located on the high side of the line.
Five amp input capability allows the output of 5 A
current transformers to be applied directly to the
meter, with no need for a stepdown transformer. The
current reading can easily be scaled to display the
input to the current transformer. Digital scaling
and calibration eliminate zero and span drift
associated with potentiometers in non-microcomputer
based meters. |
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High
Accuracy |
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The
typical accuracy is 99.9% of full scale, decreasing
to 99.8% for low frequency at high amplitude, or
high frequency at low amplitude. The above graph
shows that maximum error is 0.1% of full scale over
all frequency ranges of interest to AC power
measurement. Error increases to 0.2%, represented by
the two shaded areas, at low frequency and high
amplitude, or high frequency and low amplitude.
Crest factor increases in inverse proportion to
signal amplitude. As shown on the same graph, the
maximum crest factor (Vp / Vrms) is 2.4x at
full-scale amplitude, increasing to 240 at 1% of
full-scale amplitude.
The Laureate True RMS AC ammeter utilizes the same
high-speed analog-to-digital conversion method as
all other Laureate digital panel meters. However,
the meter settling time and control response to a
step change in AC amplitude are limited by the True
RMS AC converter circuit to approximately 1 second. |
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Interface
Options
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Built-in
Flexibility & Safety
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Plug-in
isolated analog output, dual setpoint controller,
and RS-232, RS-485 communications or BCD output
boards can upgrade the digital panel meter from a
simple monitor to system interface and control.
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Laurel AC ammeters may
be powered from 85-264 Vac and 90-370 Vdc, or
optionally from 8-28 Vac and 9-37 Vdc. They are
available with red or green LEDs. They are housed in
a 1/8 DIN case that meets NEMA 4X (IP65)
specifications from the front when panel mounted.
Any setup functions and front panel keys may be
locked out for simplified usage and security.
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to Order RMS Voltage & Current Panel Meter
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Specifications |
| AC
Voltage (1% to 100% of full scale) |
AC
Voltage Range |
Resolution |
Input
Ohms |
Typ
Error at 25°C |
200.00
mV
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10
µV
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22
M
|
0.1%
FS
± count,
10 Hz to 10 kHz |
| 2.000
V |
100
µV
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22
M |
20.000
V
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1
mV
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1
M |
| 200.00
V |
10
mV
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1
M |
| 660.0
V |
100
mV |
1
M |
| AC
Current (1%
to 100% of full scale) |
AC
Voltage Range |
Resolution |
Input
Ohms |
Typ
Error at 25°C |
| 2.0000
mA |
0.1
µA |
100
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0.1%
FS
± count,
10 Hz to 10 kHz |
| 20.000
mA |
1.0
µA
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10
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200.00
mA
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10
µA
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1
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| 5.000
A |
1.0
mA |
0.01 |
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AC
Voltage & Current |
| Accuracy |
Maximum
Signal |
| Span
Tempco |
0.0015%
of reading/°C
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Max
applied
voltage
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660
Vac for 20, 200 and 600 V ranges, 125 Vac for other
ranges |
| Zero
Tempco |
0.1
µV/°C |
Overcurrent
protection |
25x
for 2 mA, 8x for 20 mA, 2.5x for 200 mA, 1x for 5 A |
| Crest
Factor |
2.4x
at 100% of full scale |
----- |
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| Response
Time |
Display |
| RMS
to DC |
1
s conversion settling time |
Readout |
5
digits, 7-segment, 14.2 mm (.56") |
| A-to-D
Rate |
60/s
at 60 Hz, 50/s at 50 Hz |
Color |
Red
or green LED |
| Output
Update |
56/s
at 60 Hz, 47/s at 50 Hz |
Range |
-99999
to +99999 or -99990 to +99990 (count by 10 with
rounding) |
| Display
Update |
3.5/s
at 60 Hz, 3/s at 50 Hz |
Indicators |
2
red LED lamps |
| Power |
Excitation
Output |
| Voltage,
std |
85-264
Vac and 90-370 Vdc |
5
Vdc |
5
Vdc ±5%, 100 mA max |
| Voltage,
opt |
8-28
Vac and 9-37 Vdc |
10
Vdc |
10
Vdc ±5%, 120 mA max |
| Frequency |
DC
or 49-440 Hz |
24
Vdc |
24
Vdc ±5%, 50 mA max |
| Power
isolation |
Safety-rated
to 250 Vac, meter ground to earth ground,
DC to 60 Hz, 4.2 kVp per High Voltage Test |
Output
isolation |
50
Vdc to meter ground |
| Environmental |
| Operating
Temperature |
0°C
to 55°C |
| Storage
Temperature |
-40°C
to 85°C |
| Relative
HumidityProtection |
NEMA-4X
(IP-65) when panel mounted |
| Connector
Pin Assignments |
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to Order RMS Voltage & Current Panel Meter
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Using
Laureate Meters and Counters to Instrument an AC Line
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Why Measure AC
Power?
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Many AC loads, such as
electrical motors, will only operate reliably if the AC line
voltage and frequency are within specified tolerances. Otherwise
permanent damage to expensive plant equipment may occur.
Motor generators and UPS systems will only
operate reliably with the load for which they are rated. Drops in
line voltage or frequency may indicate an excessive load and the
possibility of equipment damage.
Laureate meters and counters are
low-cost means to instrument AC power lines with great accuracy:
AC RMS Voltmeter. Full-scale
ranges of interest are 200.00 V with 10 mV resolution and 660.0 V
with 100 mV resolution. True RMS capability allows the display of
RMS voltage for non-sinusoidal waveshapes, such as square waves
from a UPS.
AC RMS Ammeter. A
built-in 5 A range can be used to display currents up to 5.000 A
with 10 mA resolution, or to accept the output of 5 A current
transformers. The 200.00 mV range can be used with external
current shunts. With either transformers or shunts, scaling to
the input current is easily accomplished via the meter's front
panel pushbutton switches.
Frequency Meter. Inverse
period is used to determine AC line frequency to six-figure
accuracy (60.0000 or 50.0000) in a few line cycles plus 30 ms.
Phase Angle Meter.
Two signals with identical periods are applied to Channels A and
B of the Laureate phase angle meter. A display from -180º to
+180º is obtained by timing the rising edge of one channel and
the falling edge of the other channel. A resolution of 1º, 0.1º
or 0.01º is selectable. Accuracy is .01% up to 100 Hz, .1% at 1
kHz, and 1% at 10 kHz.
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Using
Laureate Meters to Synchronize Motor Generators
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Successful synchronization of two
motor generators requires that the voltage outputs of the
generators be close to each other, that the two frequencies be
identical, and that the voltage waveshapes be in phase.
The two voltages
can be measured by two Laureate AC RMS Voltmeters, which offer
200.00 V and 660.0 V ranges. Or a single meter can be multiplexed
by using an external toggle switch.
The two frequencies
can be measured to six-figure accuracy by a single Laureate Dual
Channel Counter, where each channel monitors a generator. The two
AC neutrals must be tied to meter ground. Pressing a front-panel
key toggles the reading between the channels.
Phase angle
can be measured using the Laureate Dual Channel Counter.
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to Order RMS Voltage & Current Panel Meter
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FLW,
Inc - 3505
Cadillac Ave - Bldg E - Costa Mesa, CA. - 92626 - USA - Ph (714) 751 -
7512 - Fax (714) 751 - 0213
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