HIOKI · APPLICATION GUIDE
Short answer: A useful data centre cooling study measures electrical load, temperature, humidity and heat flow under the same operating conditions. Synchronized data helps engineers connect server demand to thermal response, locate hot spots, quantify cooling-system energy and confirm that an efficiency change does not compromise equipment reliability.
- Measure the cause and the thermal response on a common timeline.
- Select the logger, modules and sensors around the required channels, speed and installation points.
- Use facility and IT energy from equivalent periods when calculating PUE.
AI servers and other high-density computing systems can increase rack power and heat load quickly. A room-temperature reading may show that the data hall is within its target range while still missing a recirculation path, a local hot spot, a short cycling event or an inefficient cooling response.
The stronger method is to record several related quantities together: power consumed by the IT and cooling equipment, temperature at selected rack and airflow locations, ambient humidity, and heat movement through a cooling component or surface. The result is a time-aligned record that can support troubleshooting, commissioning and before-and-after efficiency studies.
Why measure power and temperature together?
Power is a major input to the thermal system. Temperature is the response, but it can lag behind a load change and can vary sharply between the inlet, outlet and surrounding air. Recording only one side of this relationship makes it difficult to determine whether a temperature rise came from higher IT load, reduced airflow, control behaviour or another operating change.
A shared timeline lets the team compare an electrical event with the thermal response that follows. Add humidity when environmental limits or condensation risk matter. Add heat-flow measurement when the question concerns heat transfer through a cold plate, pipe, enclosure, insulation layer or other surface rather than air temperature alone.
| Measurement question |
Useful data |
Relevant HIOKI approach |
| How does rack or cooling load affect temperature? |
Time-aligned power and multi-point temperature |
LR8102 Data Logger with suitable measurement modules |
| Are environmental conditions stable across the hall? |
Temperature and relative humidity at selected locations |
LR8514 Wireless Humidity Logger |
| Where and when is heat moving through a surface? |
Heat flow, temperature and voltage |
LR8432-20 Heat Flow Logger with suitable heat-flow sensors |
| How much energy does a circuit use over the study period? |
Power, demand and energy trend data |
PW3360-21/100Pro Clamp-On Power Logger Kit |
Configure the LR8100 Series for the application
The HIOKI LR8101 and LR8102 are modular data loggers. The measurement module determines the channel count, measurable quantity and sampling options, so the configuration should begin with a channel map rather than the logger alone.
M7100 for faster voltage and thermocouple measurement
The M7100 provides 15 isolated voltage or thermocouple channels. It can capture all enabled channels at 10 ms intervals and can reach 5 ms when no more than eight channels are used, all are set for voltage and the applicable logger and output conditions are met. This can suit concentrated measurements where response time and channel isolation matter.
M7102 for higher channel density
The M7102 Voltage/Temperature Module provides 30 isolated channels and sampling as fast as 10 ms under the applicable channel-use conditions. Its higher channel density can reduce the module count for a large temperature map across rack inlets and outlets, air-handling equipment or liquid-cooling test points.
M7103 for integrated power measurement
The M7103 provides three power-measurement channels per module. Combining power and temperature modules in a modular LR8100 setup can help keep electrical and thermal results on a coordinated time base. Confirm the circuit type, voltage, current sensor, channel count and required accuracy before finalizing the system.
Monitor data-hall temperature and humidity
Environmental mapping should reflect the question being investigated. Useful locations may include the rack inlet and outlet, hot and cold aisles, supply and return paths, high-density zones and areas with suspected recirculation. Sensor placement, response time and shielding from direct airflow can influence the result as much as logger resolution.
The HIOKI LR8514 records temperature and humidity from two optional sensors, providing two temperature and two humidity channels. It stores up to 500,000 data points per channel and can operate as a compact standalone logger or transfer data wirelessly. That makes it useful when wiring a central logger to every point would be inconvenient.
Measure heat movement, not only temperature
Temperature indicates a condition at a location. Heat flow indicates movement of thermal energy through a surface. This distinction can help when evaluating insulation, tracing heat paths, comparing cooling interfaces or determining whether heat is entering or leaving a component.
The HIOKI LR8432-20 is a ten-channel logger designed for heat-flow, temperature and voltage measurement. With suitable HIOKI heat-flow sensors, it can record heat-flow and temperature data together and supports calculation functions such as averaging, integration and heat-transfer-coefficient processing. The sensor size, sensitivity, mounting method and surface condition must be matched to the test object.
Record facility and cooling-system energy
Long-term power logging can show how chillers, pumps, fans, computer-room air handlers and other cooling loads change with IT demand and operating conditions. The HIOKI PW3360-21 supports single- and three-phase circuits, demand and energy recording, and harmonic analysis through the 40th order. The kit and current sensor must match the conductor, circuit and expected current.
Where connecting to exposed voltage terminals is difficult, the HIOKI PW3365 uses fully covered voltage sensors for non-metallic-contact voltage measurement on suitable insulated conductors. It supports single- through three-phase four-wire circuits and long-term recording. This method still requires qualified personnel, an approved job plan and confirmation that the conductor construction and measurement range are compatible.
For PUE studies, use the standard relationship PUE = total facility energy ÷ IT equipment energy. Both values must represent the same time period and operating boundary. A short snapshot can be useful for troubleshooting, but it should not be presented as a representative annual efficiency value.
A practical data centre cooling measurement workflow
- Define the decision. State whether the study is intended to locate hot spots, validate a control change, compare cooling modes, commission equipment or establish an energy baseline.
- Draw the measurement boundary. Identify the IT loads, cooling loads, electrical circuits, airflow paths and surfaces included in the study.
- Create a channel map. List each power, temperature, humidity and heat-flow point, its expected range and the required recording interval.
- Synchronize the records. Align clocks and start times so that a load change can be compared with the thermal response.
- Run a baseline. Record stable operation before changing setpoints, airflow, workload or cooling configuration.
- Change one controlled variable. Document the change, stabilization time and any unrelated facility events.
- Review trends together. Compare electrical load, temperatures, humidity and heat flow instead of interpreting each graph in isolation.
Configuration and support in Canada
RCC Electronics supports Canadian data-centre operators, commissioning teams, consultants and facility engineers with HIOKI configuration guidance. Share the circuit type, expected current and voltage, number of thermal points, required sampling interval, installation constraints and study duration so the logger, modules, sensors, leads and storage can be reviewed as one system.
Exact availability, included accessories and calibration requirements depend on the selected configuration. Contact RCC Electronics before ordering when the application involves many channels, high voltages, unusual conductors or coordinated power and thermal measurement.
FAQ: Data centre cooling measurement
Is room temperature enough to evaluate cooling performance?
No. A room average can hide rack-level hot spots and recirculation. Measure at the locations that represent the equipment inlet, outlet and suspected airflow paths, and compare those temperatures with electrical load.
When should power and temperature be logged together?
Log them together when the goal is to relate a workload or cooling-energy change to a thermal response. A common timeline makes lag, cycling and short events much easier to interpret.
When is humidity measurement useful?
Humidity is useful when environmental compliance, condensation risk or seasonal changes are part of the study. Select sensors and locations that represent the air reaching the equipment rather than a convenient wall location.
What is the difference between temperature and heat-flow measurement?
Temperature describes the condition at a point. Heat-flow measurement indicates thermal energy moving through a surface, which can reveal a transfer path before a large temperature change appears.
How long should a cooling study run?
The recording period should cover the operating cycles and load conditions that matter. Troubleshooting may take hours; energy baselines and PUE studies usually need longer periods that capture daily, weekly or seasonal variation.
Can RCC Electronics help select modules and sensors?
Yes. RCC Electronics can review channel count, measurement range, sampling needs, conductor access, sensor placement and data-handling requirements for a Canadian application.
Plan a measurement system around the decision you need to make
RCC Electronics can help match HIOKI loggers, modules and sensors to your power and thermal measurement points.
View HIOKI LR8102 Contact RCC Electronics
* Specifications are summarized from manufacturer-published information and should be confirmed against the latest official HIOKI datasheets before final selection. Measurement limits and fastest sampling intervals depend on the logger, module, channel configuration and operating settings.
