DISPLAY UNIT CM7290

Multi-functional Display Unit to Use Right on the Field or
Output to Advanced Recorder or Logger
Exclusive Academic Offer

Hioki clamp on meters are best-in-class measuring devices incorporating
Hioki’s expertise in current sensing technology. The CM7290 is the display
and output unit for the CT7600 and CT7700 AC/DC Current Sensor series,
creating a standalone clamp meter for field use or enabling waveform signals
to be output to a Hioki memory recorder or logger for further analysis.

Model No. (Order Code)

CM7290For the CT7000 series

CEDROPPROOF

 

Key Features

• Power supply and signal output for Current Sensor CT7000 series
• Simultaneous dual display of the measured values, frequency, and output rate
• Four output formats to output data to loggers or other devices (via Display Unit)
• Supports AC adapter, AA alkaline batteries, and external power supply

Note: CM7290, CM7291 cannot be used alone. Use with CT7000 series.
When used in combination with the CT7000 sensor series, the frequency
band for current display and waveform output is narrower than the sensor band.


Current Measurement Using an AC/DC Current Sensor:
Basic Measurement Settings

By connecting an AC/DC current sensor to the Display Unit CM7290 and the Display Unit to a data logger or Memory HiCorder, you can output:

• A DC or AC (up to 5 kHz/10 kHz) current waveform as-is
(using WAVE mode for waveform output)
• An analog signal generated by converting the input waveform to a series of RMS values
(using RMS mode for RMS output)
• An analog signal generated by detecting the current waveform’s peak value
(using PEAK mode for peak output
• An analog waveform generated by detecting the frequency of the current waveform
(using FREQ mode for frequency output)

Current Measurement Using an AC/DC Current Sensor:
Compatible Current Sensors

You can use any of a selection of available AC/DC current sensors with ratings ranging
from 100 A to 2000 A. The CM7290 supports two types of current sensor: AC/DC Auto-zero
Current Sensors, which have a sensor frequency band ranging from DC to 5 kHz AC, and
AC/DC Current Sensors, which have a frequency band ranging from DC to 10 kHz AC.

Current Measurement Using an AC/DC Current Sensor:
Auto-Zero Current Sensor Functionality

Because temperature variations cause the zero-point to shift when using a conventional DC
current sensor to measure DC current, it is necessary to perform zero-adjustment
periodically when recording data over an extended period of time with such a sensor.
This shortcoming is caused by the effects of the Hall element that conventional DC
current sensors use to to detect current. Hioki’s new auto-zero current sensors
incorporate a new switching-based offset cancellation circuit developed to address
this problem. The new design minimizes zero-point shift, making it possible to
record DC current values over an extended period of time without the need for
periodic zero-adjustment.

Current Measurement Using an AC/DC Current Sensor:
WAVE Waveform Output Function

The Display Unit CM7290 converts the current waveform for current flowing in a wire to which
an AC/DC current sensor has been applied to a proportional voltage signal. By inputting that
signal to a digital oscilloscope or Memory HiCorder, you can measure instantaneous AC or DC
current waveforms such as a motor’s starting current waveform. Alternatively, by using the
CM7290’s WAVE waveform output function in combination with a data logger, you can observe the
DC current generated by a PV system’s solar panels over extended periods of time. Auto-zero
current sensors are ideally suited to applications in which a DC current must be observed
over an extended period of time.

Current Measurement Using an AC/DC Current Sensor:
RMS Mode for RMS Output

In this mode, the Display Unit CM7290 converts the current waveform for current flowing in a
wire to which an AC/DC current sensor has been applied to a series of RMS values. It then outputs the result as a voltage signal (FAST: 45 Hz or greater, NORMAL: 10 Hz or greater, SLOW: 3 Hz or greater). This configuration
is ideally suited to applications such as AC current measurement on the power supply side
of a welding machine, which is characterized by abrupt current fluctuations, or long-term
measurement of RMS values for the current waveform from an inverter operating at varying
frequencies or a machine tool’s spindle motor.

Current Measurement Using an AC/DC Current Sensor:
PEAK Mode for Peak Output

In this mode, the Display Unit CM7290 detects the peak value of the current waveform for current flowing in a
wire to which an AC/DC current sensor has been applied at the rate of 2 kS/s (= 500 μs). It then outputs its absolute value as a voltage signal with an output refresh time of 0.02 s (FAST), 0.2 s (NORMAL), or 1 s (SLOW).
This configuration is ideally suited to applications in which the maximum current value of a
rapidly fluctuating power supply line or load must be continuously recorded.

Current Measurement Using an AC/DC Current Sensor:
FREQ Mode for Frequency Output

In this mode, the Display Unit CM7290 calculates the frequency of the current waveform for current flowing in a wire to which an AC/DC current sensor has been applied at the user-specified interval. It then outputs the result as a voltage signal with an output refresh time of 0.2 s (FAST), 0.2 s (NORMAL), or 3 s (SLOW). In this configuration, the CM7290 can be used in applications such as frequency fluctuation inspections and testing of compressors and motors.

Basic specifications (Accuracy guaranteed for 1 year, Post-adjustment accuracy guaranteed for 1 year)
* Waterproof characteristics intended to maintain measurement function; measuring energized parts while instrument is wet will increase risk of electric shock.

SensorCT7642, 7742CT7636, 7736CT7631, 7731
Measurement parametersDC, AC, DC+AC, Hz
Crest factor3 at 5000 count or 2.5 at 6000 count for AC and DC+AC
Output methodWAVE, RMS, PEAK, FREQ
Input connectorsHIOKI PL 14
Output update timePEAK--- FAST: 0.02 s / NORMAL: 0.2 s / SLOW: 1 s
FREQ--- FAST: FAST: 0.2 s / NORMAL: 0.2 s / SLOW: 3.0 s
(WAVE, RMS: analog output)
PEAK sensing duration2 ms or greater
(during PEAK MAX/PEAK MIN and PEAK output)
Other functionsAuto range, Zero adjustment at power-up, Analysis display, Filter, Output amplification, Display value hold, Backlight , Auto-power save, Save settings, keypad lock
Typical accuracy (WAVE output DC)±2.0% rdg. ±10.8 mV
(60.00 A range)
±2.5% rdg. ±30.8 mV
(60.00 A range)
±1.5% rdg. ±5.8 mV
(60.00 A range)
Typical accuracy (RMS output AC)±2.3% rdg. ±10.8 mV
(60.00 A range)
±2.8% rdg. ±30.8 mV
(60.00 A range)
±1.8% rdg. ±5.8 mV
(60.00 A range)
Power supplyLR6 alkaline batteries (AA) ×2, Continuous use: 16 h (backlight OFF and WAVE or RMS output, when used with CT7600s), Rated power 2.5 VA
or AC adapter 9445-02/03 (100 to 240V AC), or 5 to 15 V DC external power supply, Rated power 2.5 VA
Dust and water resistance *IP54 (with sensor connected and caps fitted to AC adapter and power connector)
Dimensions and mass52 mm (2.05 in)W × 163 mm (6.42 in)H × 37 mm (1.46 in)D, 220 g (7.8 oz) (including protector and battery)
AccessoriesLR6 alkaline batteries ×2, Protector ×1, Instruction manual ×1
Catalog: AC/DC CURRENT SENSOR CT7000 Series, DISPLAY UNIT CM7290, CM7291Download PDF  [4MB]English

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