Electrical technology

Data loggers are taking on a whole new look in today’s market. Some are the size of matchbooks, while others take up huge racks. Many of the old-style units needed to be hard wired and placed near the area where the tests were carried out.

Data loggers of the past were basically used to monitor low voltage levels with very little isolation between channels. Remember those noisy relays you use to hear when they were first introduced? Now everything is solid state – silent.

Old models were slow in their scan speed, and weren’t the most dependable when doing long-term measurements. They had no memory, or only a few kilobytes, and only the expensive units had serial output to get some raw data out.

With the technology we have today, new loggers such as the Hioki LR8410-20, all kinds of different signals can monitor things such as current, temperature, humidity, pressure, load, flow rates and such.

Separate trigger points can be set for each channel, engineering units can be set for independent channels, alarms, scaling functions and so on. These new units now have LAN and USB ports built into them, can stream the data directly to SD memory cards or external hard drives and PCs.

Also, if you wanted to monitor a large area spread over hundreds of metres you needed multiple units, which was also a problem. How can we accomplish this? How can we monitor signals such as temperature, humidity, sensors, up high such as in a warehouse, silo, and attic or over long distances? How can we collect signals from multiple points around a building, while keeping the data synchronised so it can be compared on the same time axis?

For example, monitoring multiple burn-in racks or ovens, all coming into one main logging station can become costly. Up until now, multiple loggers had to be used, lengthy and costly wire runs had to be made, while trying to keep the induced noise, degraded signal due to cable loss to a minimum. This becomes extremely costly, and most of the time the data from these signals becomes error-ridden.

With the introduction of the new wireless loggers that are being introduced such as the Hioki LR8410-20 logger, logging multi-point data has never been so easy. Wireless technology makes it possible to log data in applications where it would have been difficult to use a conventional logger, such as high locations where wiring would be difficult to install, or inside secured control panels.

The separate logging modules can be placed right next to the systems to be measured reducing the connection complexities. Individual low cost wireless logging stations using Bluetooth technology are placed near the devices that need to be monitored.

The data is then sent wirelessly from the Hioki logging modules to the Hioki wireless logging station in real time mode. The data can then be stored directly to the logger’s internal memory or saved to its removable SD card.

Fuel cell testing

Need to monitor the voltage, current, temperature, and humidity on multiple l high voltage fuel cell stacks? Using the Hioki IR8410-20 logger, humidity sensor, current clamps are connected to the cell under test, the inputs scaled and engineering units are entered so the logger displays the appropriate readings.

Thermocouples are placed on the fuel cell stack to measure the temperature of the cells with the logger doing the cold junction compensation.

What is also important to realise is there is a potential of high voltage on these stacks that does not affect the loggers accuracy and measurements. Also, the need to monitor multiple fuel cell stacks at one time makes this a simple task for the Hioki LR8410-20 by putting LR8500 logger modules next to each fuel cell stack and having the modules communicate back using its Bluetooth technology.

Monitoring ovens

In one case, seven ovens needed to be monitored, with 12 channels of temperature and humidity in each oven. Eight, 12 channel loggers would need to be installed, and then hard-wired back to a central PC workstation.

Challenges included data not being synchronised across all ovens, individual cabling needed d to be run to each logger (in a not so friendly area), and d the cost of each logger with appropriate interface was high. Customer tried to share one logger for every two ovens, but wiring individual channels became a problem with cable run and induced noise. Set-up time approximately 10 days.

Battery discharge rate

A customer needed to monitor battery discharge rate of a wheelchair, over time, movement and load. Using one Hioki data logger, the company ran a test on one wheelchair at a time to get information such as DC voltage, current, discharge rate, rotation of wheels, load and runtime.

Mounting the older Hioki 8421 series data logger the unit was able to capture this information store it to a memory card and later loaded onto a PC for evaluation.

Using the new Hioki LR8410-20 logging system the manufacture mounted the LR8510 logger modules with rechargeable battery packs on multiple wheelchairs. These units communicated back via Bluetooth to the main LR8410-20 logging collector with the same data that one unit collector only on multiple wheelchairs at the same time.

They ran multiple tests at once, saving valuable time

and allowing them to compare different products immediately by comparing signals in real time. This saved the valuable time and money, and allowed the firm to show some major differences between products.

Conclusion

New loggers scan speeds in millisecond across multiple channels. Plus many of these units have event search functions. Logger utility PC software is also available to evaluate the data after it has been collected, view past data during recording, and output this data to a printer to generate graphs and reports.

Go to demm.co.nz/ enquiry quote: D140733