Engineering Excellence for Maritime and Energy

Power take off rigs

Novel designs of power take off systems may include new generator types, new gear box designs, hydraulic pumps and so on. At Lir, we have a suite of equipment design to test, evaluate and calibrate these systems. The novel PTO devices can be connected to either linear or rotary actuators. Data acquisition and power dissipation can be configured as required to meet the needs of the developer.




This rotary test rig consists of a standard 6 pole, 975 rpm, 15 kW machine mounted on a skid operated from a universal variable speed ac Emerson UniDrive. Multiple PTO shaft size options are available to match different diameter generators, gearbox options are also available for different ranges of speed.

The rotary PTO test rig, together with components of the microgrid, provides a range testing options to developers for their initial scaled test device, at various speeds and load profiles.

Suitable electrical loading to the generator can be supplied and power quality produced monitored. The test setup can be used to characterise a novel generator and/or PTO mechanism under a range of operating conditions and control laws.




Many types of ocean energy devices have a linear power take off system. At Lir a ¼ scale linear electromechanical test rig has been built to emulate the linear motion induced by the waves. An electrical servomotor with a rotation-to-translation gearing system is used to control the piston linear motions and the motion is accurately measured on a resolver connected to the servomotor. This motion can be used to calibrate PTO systems or mooring line force-extension characteristics.  The rig is rated at 20 kW, 1 m/s, 1.8mm/s2 and 15 kN with a stroke length of 900mm. Device developers bring their scaled prototypes to Lir-NOTF for characterisation and analysis. Valuable lessons about the controllability, lifetime analysis and stress testing of the prototype can be learned. The system is controlled using an industrial standard PLC and HMI, to ensure safety of equipment and personnel.

Related projects

Mooring Testing

Power Take Off Testing


samllLinearThe linear PTO test rigs are designed to emulate the linear motion induced by waves and are capable of generating any linear motion time series within the limits provided in the table below. This motion can be used to calibrate PTO systems or mooring line force-extension characteristics. A piston and cylinder are available to simulate an Oscillating Water Column and calibrate pneumatic orifices at around 1:50 scale. The test rig is equipped with a National Instrument CompactRIO for data acquisition and control of a large range of sensors or actuators.

Small linear PTO test rig Large linear PTO test rig
Linear stroke 280 mm 900 mm
Linear force 640 N 15 kN
Motor torque 2 Nm 65 Nm
Speed 0.6 m/s (250rad/s) 0.9 m/s
Acceleration 2.5 m/s2 (1250 rad/s2) 1.78 m/s2
Minimum period in sinusoidal motion 1.5 sec. with 250 mm stroke 900 mm stroke in 1.5 sec
0.5 sec. with 50 mm stroke