Turbine Sensor Test Results

 

TEST REPORT SUMMARY

The following table shows the test results obtained from both Creative Instrumentation Limited testing of turbine sensor FTS7010-AMS issue 01 over 500 thermal cycles to 1000˚C and Fylde Electronic Laboratories Limited testing of the same sensor after 500 cycles to 1000˚C

 

PURPOSE OF TESTS

The purpose of the Creative tests was to confirm that the sensor would survive repeated thermal cycles from room temperature to the following operating temperatures whilst maintaining both hermeticity and primary IR and Capacitance characteristics.

 

Sensor Tip: 1000˚C     Body Lower: 800˚C     Body Upper: 650˚C     MI Cable: 650˚C

 

The purpose of the Fylde tests was to determine overall calibration system accuracy and repeatability of the sensor by performing dynamic calibrations against a spinning target at similar operating conditions with the sensor tip set at 1mm distance from the target.

Sensor Type

Turbine Sensor FTS7010-AMS issue 01

MI Cable Diameter

3.50mm

Cable Lengths               

Creative:   2 metres MI Cable + 20m flexible extension cable
Fylde:    2 metres MI Cable + 4m flexible extension cable

Thermal Cycles Completed

500 cycles from room temperature to 1000°C

Sensor Hermeticity

100% at all conditions

Sensor “Tune” Functionality

100% at all conditions

Sensor Isolation Resistance

> 5GΩ at room temperature
> 85kΩ at maximum operating temperatures

Noise Levels

Generally better than 100mV peak to peak

Sensitivity

0.3843 μm /mV

System Accuracy

Sensor Tip: 1000°C / Sensor Body: 800°C

600mm MI Cable: 650°C

Better than 1.5% of target distance of 1mm

System Accuracy

Sensor Tip: 1000°C / Sensor Body: 800°C

1200mm MI Cable: 650°C

Better than 2% of target distance of 1mm

Average System Repeatability

Better than 0.7% of reading at room temperature Better than 1.2% of reading at max temperatures

General Observations

 

TEST RESULTS SUMMARY

The tests were conducted in the period from October 2019 until December 2020 and successfully demonstrated that sensor performance was within the operational limits outlined below: A copy of the full test report is available on request.

 

REQUIRED SENSOR LIFE

When determining the required sensor life a number of different factors govern each customer requirement. However 500 thermal cycles generally corresponds to 2-3 years operation at DSS (Daily Start and Stop) or WSS (Weekly Start and Stop) mode and so a target figure of 500 thermal cycles from ambient to maximum operating temperatures was adopted as the basis of the sensor test programme.

 

MINIMUM ISOLATION RESISTANCE LEVELS

Past laboratory tests with commercially available sensors and electronics have shown that if sensor isolation resistance (IR) drops below 30kOhms then significant measurement errors will occur and below 1kOhm the signal can be lost, so any production sensor must be able to achieve and maintain an IR of at least 50kOhm at all operating conditions.

 

Ø2.5mm and Ø3.5mm MI CABLE OPERATING TEMPERATURES

The laboratory test results show the measurement accuracy and repeatability for turbine sensors with both 600mm and 1200mm of Ø3.5mm Triaxial MI Cable heated to 650°C. In practice, the corresponding length of Ø2.5mm Triaxial MI Cable that can be heated to 650°C whilst maintaining the stated accuracy and repeatability figures is 380mm and 760mm respectively.

 

MAXIMUM MI CABLE OPERATING TEMPERATURES

It is important to note that although the testing at Creative and Fylde was performed with MI cable temperatures up to 650°C additional testing at Creative proved that the MI cable can be heated to 800°C and the sensor will remain in tune with the Fogale electronics. However, at 800°C the MI cable is at the limit of it’s operational capability and so to achieve a long life it is more realistic to operate the cable at 650°C which is more representative of actual engine operating conditions.

 

MEASUREMENT SYSTEM ACCURACY AND REPEATABILITY

The measurement system accuracy and repeatability statements relate to the overall calibration process and include a number of experimental errors as well as any errors introduced by the sensor and MI cable.