Application: General Electric MS5001D, K, L and LA gas turbines

Diesel engines are used to start GE gas turbines with “black start” capability.  The Cummins 300 series diesels were installed on MS5001D, K, L and LA gas turbines of the 1960s and were rated at about 350 horsepower.  The power contributions from the engine, torque converter, and hydraulic ratchet (rotor turning mechanism) were needed to “break away” the gas turbine. 

There are high torque requirements of the gas turbine rotor when it is at rest (zero rpm); hence the ratchet is needed to assist in the turning of the rotor.  Once the turbine rotor is spinning and the ratchet is stopped, the torque requirements diminish significantly.  Later, at higher speeds as the compressor becomes more efficient, the torque requirements increase again.  Once the gas turbine is “fired,” it assists the diesel to bring the turbine up past 65 percent speed.  At that speed, the clutch disengages, and the diesel is brought down to idle speed for cooldown.  Thereafter, the turbine continues up to full speed/no load (FSNL) under its own power.

Fig. 1: Typical 300 series Cummins diesel starting engine for GE gas turbines

These original 350 HP diesels (non-supercharged) were observed to be “marginally rated” even when new.  Modifications were done by owners to cool the oil going to the torque converter to assist the starting means, particularly in hotter climates.  Furthermore, hot restarts of the gas turbine, particularly after unplanned turbine trips, were often difficult with the 300 series diesels, primarily due to the reduced efficiency of the torque converter. 

Fig. 1 above shows an engine ready for removal.  The fin-fan drive of the turbine’s cooling-water system shown removed to increase working space for diesel engine rigging and lifting.  The roof of the accessory compartment that includes the turbine and diesel cooling water system has been removed as well. 

Reconditioning “tired” Cummins 300 series engines has become virtually impossible.  Spare parts and rebuild kits are no longer available.  That’s the bad news.  However, Cummins did manufacture an industrial-grade, replacement engine that is adaptable and whose parts are readily available.  A Cummins 903 engine was found and adapted from an industrial application by affiliate company, Haberek Diesel Machine of Amsterdam, NY.

It was fully reconditioned and tested before installation under PAL Engineering’s supervision at an electric utility in Lexington, Kentucky.  See Fig. 2 below.

Fig. 2: Cummins 903 rebuilt and tested by Haberek’s of Amsterdam, NY

Pond and Lucier, LLC (PAL Engineering) can provide a complete, turn-key replacement of the original Cummins 300 series engine with a “peppier” Cummins 903, as shown below in Figure 3. The torque converter from the original 300 series is being reused.  It can be reconditioned, if necessary.

Fig. 3: Cummins 903 engine is connected to original torque converter