HIOKI · APPLICATION GUIDE
Short answer: Recording a chiller drive's voltage and current waveforms can help engineers investigate intermittent electrical events and compare drive behaviour with motor, vibration and temperature measurements. A suitable multi-channel recorder captures signals on a shared timeline, giving maintenance teams more evidence when diagnosing cooling-system problems in a data centre.
- Capture drive output and relevant operating signals together.
- Use the right isolated inputs, sensors and trigger for the event.
- Compare the waveform with mechanical and thermal trends.
High-density computing places sustained demands on data centre cooling. A chiller's compressor, motor, variable-frequency drive (VFD), heat exchangers and controls operate as a system; a disruption in one part can affect cooling performance and availability.
Temperature, pressure, liquid level and vibration measurements provide important context. Electrical waveforms add another view of the drive and motor, especially when a problem occurs only during startup, a load transition or an occasional trip.
What can a chiller drive waveform reveal?
A VFD controls a motor using switched output voltage, commonly pulse-width modulation (PWM). Recording voltage and current alongside a control or operating signal lets an engineer examine what happened before, during and after an unusual event. Waveform differences are clues to investigate, not a diagnosis on their own.
Compare recordings with a known operating baseline and the drive manufacturer's guidance. Load, speed, switching frequency, sensor bandwidth, probe placement and recorder settings all affect the shape shown on screen.
| Question |
Signals to consider |
Useful context |
| What happened around a trip? |
Drive voltage, current and trip/control signal |
Trigger and sufficient pre-event recording |
| Does electrical behaviour change with load? |
Motor current, voltage and speed or command signal |
Operating mode, load and comparable baseline |
| Is an electrical event associated with a mechanical change? |
Electrical channels plus vibration or another transducer output |
Sensor placement and a common time reference |
Capture voltage and current at the drive
Start by identifying the circuit, expected voltage and current, switching behaviour, number of phases and event duration. The required input modules, voltage probes and current sensors depend on these details. Sampling rate and bandwidth must be suitable for the event being investigated; a slow trend alone may miss a short switching transient.
The HIOKI MR6000-01 Memory HiCorder is a modular high-speed recorder suited to multi-channel waveform acquisition. The HIOKI MR8848 is another multi-channel Memory HiCorder option. Both require the appropriate input modules and probes for the signals and measurement limits involved.
Correlate electrical and mechanical measurements
Drive output does not tell the whole story. Where suitable sensors and inputs are available, record a vibration or control signal on the same timeline as motor current and voltage. Temperature and pressure trends can provide slower operating context, even when collected by a separate system whose clock must be aligned.
For example, compare a current change with the drive's speed command, compressor vibration and cooling conditions. A correlation can focus the investigation, but it does not prove which component caused the event. Confirm conclusions with equipment history and additional tests.
A practical workflow for intermittent chiller events
- Define the symptom: record the alarm, operating mode, load and time of occurrence.
- Plan safe connections: qualified personnel should follow the site's electrical procedures and verify instrument, probe and input ratings.
- Choose signals: map the required voltage, current, control and mechanical channels.
- Set the capture: select sampling, trigger, pre-trigger and recording duration around the suspected event.
- Record a baseline: capture comparable normal startup, steady-state and load-change conditions.
- Compare and document: examine the event alongside operating conditions and retain the record for further diagnosis.
Plan the measurement system in Canada
RCC Electronics can help Canadian data centre and maintenance teams select a recorder, input modules, voltage probes and current sensors for the application. Share the circuit voltage and current, conductor access, expected switching frequency, required channels, event duration and safety requirements when requesting a configuration.
FAQ: Chiller VFD waveform testing
Why record a waveform instead of only an average reading?
A waveform can show short events and changes over time that an average may conceal. Both can be useful, depending on the question.
Can a waveform identify a faulty component by itself?
Usually it is one piece of evidence. Compare it with a baseline, operating data, equipment documentation and other measurements before drawing a conclusion.
Which signals should be recorded together?
That depends on the symptom. Drive voltage and current, a trip or speed-command signal, and relevant vibration or operating data are potential starting points.
Are voltage probes and current sensors included with the recorder?
Configuration and included accessories vary. Confirm the exact modules, probes, sensors and leads with RCC Electronics before ordering.
Who should connect to the drive?
Qualified personnel using approved procedures and equipment rated for the actual measurement environment.
* Based on HIOKI application information. Confirm current instrument and accessory specifications, measurement limits and safe procedures for the installation.
