The causes of this discrepancy are bandwidth and shielding. A True RMS DMM reads the heating effect of the non-sinusoidal voltage applied to the motor, while the motor controller's output voltage reading only displays the RMS value of the fundamental component (typically from 30 Hz to 60 Hz). On the flip side, a regular True RMS multimeter can't reliably read the output side of a pulse width modulated (PWM) motor drive, because the ASD applies pulse width modulated nonsinusoidal voltage to the motor terminals. A significant unbalance may lead to erratic drive operation and should be corrected when discovered. The input voltage readings should be within 1% of one another when measured from phase to phase with no load. Drive measurementsĪny good quality True RMS multimeter can verify proper input power to an ASD. Now, technicians won't have to guess whether the drive is operating correctly and delivering the correct voltage, current, or frequency for a given control setting. Incorporates a selectable low pass filter* that allows for accurate drive output measurements that agree with the motor drive controller display indicator. But until now, there hasn't been a digital multimeter on the market able to accurately measure ASDs. This is especially true when taking voltage, frequency, and current measurements on the output side of the motor drive. Likewise, choosing the right test tools for troubleshooting the drive, the motor, and the connections are of utmost importance. Nobody takes inaccurate measurements on purpose, but it's easy to do, especially when working in a high-energy, noisy environment like an ASD. As you go, take care to take accurate measurements. A lot of time and money can be wasted replacing perfectly good parts when the problem is simply a loose connection. The most efficient troubleshooting procedure begins at the motor and then works systematically back to the electrical source, looking for the most obvious problems first. The trick is tracking it down quickly and keeping downtime to a minimum. Technicians use many different methods to troubleshoot an electrical circuit, and a good troubleshooter will always find the problem - eventually. Per MIL-PRF-28800 for a Class 2 instrumentĪlkaline approximately 400 hours typical, without backlightħ.9 x 3.8 x 2" (201 x 98 x 52 mm) (with holster)Ĭlick here for complete specifications on the Fluke 87V Range: Accuracy within ±(0.2% per kHz + 0.1%) Maximum amps: 10 A (20 A for 30 seconds maximum) To make your life even easier, it fits into an optional magnetic hanger for easy set-up and viewing while freeing your hands for other tasks.ĪC bandwidth: 20 kHz with low pass filter 3 dB at 1 kHz Relative mode lets you remove test lead resistance, improving accuracy of low-resistance measurements. This unit has a removeable holster that also holds a test probe during testing for easier viewing. Removable holster with built in test lead and probe storage for convenience You also benefit from an audible Input Alert warning if the test leads are placed in the incorrect input jacks for the measurement being made. This meter is designed to withstand spikes of more than 8000 V. Touch hold keeps readings on display even after removing probesĪll the inputs are updated to the third edition of the EN 61010-1 to CAT III 1000 V and CAT IV 600 V. Large digit display with bright, two-level backlight for easier reading in low light. Analog bar graph for fast changing or unstable signals.Easy-access door for fast battery changes without breaking the calibration seal.Captures intermittents as fast as 250 μS with peak capture.Supports accurate measurements on VFDs using a low-pass filter.In addition, this multimeter includes an analog bar graph and a removable holster with storage for the test lead and probe. Efficient and safe, this industrial multimeter is designed to withstand spikes higher than 8000 V and features an audible warning if test leads are placed in the wrong input jacks.
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