Temperature is one of the most important factors that affects the performance and life of turbine engines. For the engine to be most efficient, the exhaust temperatures need to be as high as possible, while maintaining an operating temperature that does not exceed the engine’s material limits and cause damage to the engine. Too low of a temperature reduces turbine engine efficiency and thrust. Too high of a temperature will cause deterioration of the engine.
Each engine has its own specific maximum operating temperature and it is critical to be able to accurately measure these engine temperatures and ensure that the temperature sensors and temperature indicator are reading accurately.
Turbine Temperature Test Set Models
Turbine Temperature Test Sets are used by most avionics maintenance shops to measure and simulate the temperatures required for the testing of the engine’s temperature system. Turbine Temperature Test Sets are self-contained, battery-powered test sets capable of calibrating temperature indicators to over 1000°C. They can also measure temperature system lead resistances and insulation readings. They are easy to operate and provide the maintenance technician with a dependable way to test engine temperature systems that reduces testing time and keeps maintenance costs to a minimum.
The two most widely used Turbine Temperature Test Sets on the market are the TT1000A and TT1200 both manufactured by Barfield. Those test sets are specifically designed to meet the testing requirements for all turbine engine Type-K (Chromel-Alumel) thermocouple temperature measuring systems. They display the thermocouple outputs in degrees Celsius (°C) on an accurate digital display. They have a cold junction temperature circuit that automatically compensates for the ambient temperature at the test lead connection to eliminate the use of temperature tables when using other millivolt sources for temperature testing.
The Barfield TT1000A is a workhorse instrument that has been reliably used for many years. The TT1000A can measure and simulate temperature up to 1000°C with an accuracy of better than ±1 °C. It can measure thermocouples, thermocouple rings and other system lead resistances to a resolution of 0.01 Ohm and has capabilities to measure insulation values up to two Megohms.
The TT1200A is Barfield’s new microprocessor-based, Turbine Temperature Test Set. The TT1200 is designed for testing the newest digital temperature indicators. It contains all of the capabilities of the TT1000A model but also includes other features and improvements such as:
An extended temperature range up to 1200˚C needed for certain engine types
Higher accuracy and resolution of the temperature and resistance ranges
Readouts for temperatures in °C, °F, or the equivalent millivoltage readings
Large backlit 16-character alphanumeric display
Turbine Engine Temperature System Checks
Turbine Temperature Test Sets assist in the performance of the following aircraft tests:
The temperature indicator in the cockpit is removed from the aircraft instrument panel and is tested using the Turbine Temperature Test Set thermocouple output. The appropriate adapter leads are attached to the indicator terminals and the indicator is placed in its normal operating position. The temperature reading on the temperature indicator is compared with the test set readout at a variety of test points throughout the full range of the temperature indicator. The temperature compensation within the test set allows for the test to be completed without the need for ambient temperature corrections.
The resistance and continuity of the thermocouple wiring are also checked before a system function test is performed. The resistance values of the thermocouple wiring must be within very tight tolerances or the wiring will cause significant errors when read at the temperature indicator.
Once the temperature indicator and thermocouple are checked, a full functional test is completed of the entire temperature sensing system. This check is performed by using heater probes to heat the engine thermocouples to the engine test temperature. The temperature value that is displayed on the aircraft temperature indicator should be within the specified tolerance of the aircraft system and the temperature reading on the temperature analyzer.
Turbine Temperature Test Set Calibration
As with all precision testing equipment, Turbine Temperature Test Sets must be properly and regularly calibrated to ensure that they maintain the high accuracy required for the testing of engine temperature systems.
Accurate temperature calibration standards are used to simulate and measure the test set temperature indications and precision resistance standards test the resistance and insulation measuring systems.
has the precision standards and technical knowledge to properly calibrate all Turbine Temperature Test Sets to the manufacturer’s specifications. For more information on the calibration of Turbine Temperature Test Sets, contact e2b calibration.
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