Napier Turbochargers Case Study - Cells 1 and 5
Using National Instrument hardware and software to replace their old and dated manual test rigs, TBG Solutions has provided Napier Turbochargers with a solution for the
safe and efficient testing of their turbochargers.
System Design
The control and data logging system utilizes National Instruments compact FieldPoint technology. The backbone to the system is the cFP-2000 header and 8 slot backplane,
which is home to both general purpose analogue and digital input/output modules as well more specialised interface cards such as cFP-CTR-500 and cFP-TC-120.
Via an Ethernet link, the PC control software communicates with the compact FieldPoint system which allows the operators to control pumps and valves to set flow rate and
pressure via a simple and easy to use graphical user interface. In addition to the control aspect, this system also performs alarm monitoring and data logging to ensure
that the test rig remains within safe operating conditions.
Design Challenges
The initial design challenge was to prove that a computer controlled system could meet the safety requirements that Napier Turbochargers set out. Due to the shear size
of the turbocharger units, safety is paramount, and as a result the software had to immediately shut down the entire test rig when a user configured alarm limit is reached.
Warning is also provided to the operators if a signal occurs within a set tolerance of the shutdown conditions and the system had to be fail safe in the event of a computer
crash.
The next major challenge was to allow the test cell to run in both manual and automatic modes, which can be switched at any time. In manual mode the operator sets the
fuel demand to which a PID routine is applied to ensure that the fuel pump produces the desired flow rate, which has a direct effect on the turbocharger speed.
In automatic mode the operator sets a single parameter that is a function of the desired turbo speed and the temperature of the air into the turbine. Using this parameter,
the test system must control the fuel demand automatically via a PID routine whilst monitoring the turbo speed to ensure that the desired RPM is obtained. As the two modes
require different parameters and PID settings a bump-less transfer routine had to be incorporated so that the test system saw no change in signals being applied to the rig as
it is switched between modes.
System Results
This test system now allows Napier to test their turbochargers efficiently and safely. As a result the development of a further test cell is currently in the process
of being built.
Napier Turbochargers were able to leave us some feedback for our work with them. Please see their testimonial along with a few
others here.