Match Sensor Measurements to Analytics
The InsightCM Analytics Toolkit takes the guesswork out of selecting sensors for PdM. For motor-driven pumps, the InsightCM Analytics Toolkit requires three-phase voltage and current measurements to capture the dominant electrical and physical failure modes.
Taking Three-Phase Voltage and Current Measurements
High-speed voltage and current measurements include valuable data sets such as in-rush current, unbalance, and sideband measurements that are used to detect failure modes such as broken rotor bars and worn insulation.
Motor-current signature analysis (MCSA) installations use sensors that attenuate high voltage/current into levels suitable for direct instrumentation input:
- Current sensors loop around electrical connections to the motor (or the protective relay secondary inputs)
- Voltage measurements are made directly to NI instrumentation or via measurement potential transformers that connect to the same input modules as low-voltage current transformers
Figure 1. Split-core current sensors typically install in the motor control cabinet. Safety first: Always de-energize the asset/cabinet for install.
The motor-control center (MCC) makes for an easier installation point because you can monitor many motors from a single location—unlike vibration, which requires installation at each physical asset location.
SAFETY NOTE: Always de-energize equipment before working in the motor control cabinet, even when you don’t need to cut circuits for installation.
Figure 2. A single NI Continuous Monitoring System can monitor multiple assets because of the shared voltage bus and available expansion slots for current sensor input modules.
Note: The MCSA Toolkit connects InsightCM to NI Continuous Monitoring Systems for I/V measurements and is required for the InsightCM Analytics Toolkit.
Detecting Mechanical Problems with Electrical Signals
Traditionally, SMEs use voltage/current measurements to detect electrical failure modes (broken rotor bars or worn insulation) and vibration signatures to detect physical failure modes (roller-element bearing failures or shaft misalignment). But with the InsightCM Analytics Toolkit, you can extract features for both electrical and mechanical motor-driven pump components from high-speed, time-based voltage/current waveform data. Physical defects impact electrical signals through the air gap eccentricity between the rotor and stator. And we can see additional disturbances, such as indications of a worn impeller, through torque and power-spectra ripples. Configuring vibration and process data into the model provides additional failure evidence to the diagnostic engine, reinforces mechanical degradation findings, and helps you diagnose with more context.