42213 Sarah Way, Temecula, CA 92590,
Tel: 800-854-8530 (USA)
Micro Series True AC RMS
& Current Panel Meters
0.2 V - 660 V and 2 mA - 5 A full-scale
- Available in three digit heights:
0.56" for panel mounting,
5.0" (Mighty-5) for
- 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.
- 95-240 Vac ±10% and 95-370 Vdc power standard.
- Green or red display.
- Choice of isolated plug-in
options for control and computer interface:
4-20 mA & 0-10
V analog output,
RS232/485 serial I/O,
low voltage AC & DC power.
case environmentally sealed to NEMA-4X from front panel.
- 1/8 DIN
version certified to UL 3101-1, CAN/CSA-C22.2,
EN 61010-1 (CE Mark).
Micro Series True RMS meters offer 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.
True RMS meter uses 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.
Use with Current
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.
Maximum error as a function of frequency
and signal amplitude
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
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 Micro RMS meter utilizes the same
high-speed analog-to-digital conversion method as all other Micro Series panel meters.
However, the meter settling time and control response to a step change in AC amplitude are
limited by the RMS converter circuit to approximately 1 second.
output, dual setpoint controller,
RS232/485 serial communications boards can upgrade Micro
and Mighty Series meters from a simple monitor to system interface and control.
meters can be powered from
95-240 Vac ±10% and 95-370 Vdc, or
optionally from 12-34 Vac and 10-48 Vdc.
Any setup functions and front panel keys may be locked out for
simplified usage and security. The popular
DIN version with 0.56" high digits is environmentally sealed to
NEMA-4X (IP65) from the front when panel mounted, and is
available with red or green LEDs.
AC Voltage (1% to 100% of full scale)
AC Voltage Range
10 Hz to 10 kHz
AC Current (1% to 100% of full scale)
AC Current Range
10 Hz to 10 kHz
AC Voltage & Current
|5 digits, 7-segment
Available with 0.56", 1.0", 4.0" or 5.0" digits.
High brightness red. Green available
with 0.56" digits.
-99999 to +99999
-99990 to +99990 (selectable count by 10 with
2 red LED lamps
|0.005% of reading/°C
2.4x at 100% of full scale
|RMS to DC
|1 s conversion settling time
60/s at 60 Hz, 50/s at 50 Hz
56/s at 60 Hz, 47/s at 50 Hz
3.5/s at 60 Hz, 3/s at 50 Hz
|660 Vac for 20, 200 and 600 V ranges, 125 Vac for other
25x for 2 mA, 8x for 20 mA, 2.5x for 200 mA, 1x for 5 A
|95-240 Vac ±10% and 95-370 Vdc
12-34 Vac and 10-48 Vdc
DC or 49-440 Hz
Safety-rated to 250 Vac, meter ground to earth ground,
DC to 60 Hz, 4.2 kVp per High Voltage Test
|5 Vdc ±5%, 100 mA max
10 Vdc ±5%, 120 mA max
24 Vdc ±5%, 50 mA max
50 Vdc to meter ground
Connector Pin Assignments
0°C to 60°C
-40°C to 85°C
95% at 40°C, non-condensing
NEMA-4X (IP-65) when panel mounted
Meters and Counters to Instrument an AC Line
|Why Measure AC Power?
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.
Micro Series meters and counters are low-cost
means to instrument AC power lines with great accuracy:
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.
signals with identical periods are applied to Channels A and B of the
Micro 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.
Micro Series Meters to Synchronize Motor Generators
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 Micro 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
Micro Dual Channel
Frequency Meter, 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 Micro Phase Meter.
Micro & Mighty Series Downloads