Motor Details : 150 KW MOTOR 1460 RPM  269 AMPS  415 V Frame No:355L 

JJ Loughran were recently asked to carry out a full inspection report and overhaul for a critical piece of equipment in a heavy-duty quarrying application.

Once JJ Loughran received the 150KW Brook Electric motor, we utilised our advanced test equipment, to carry out the following electrical tests before overhaul to ensure the quality of the repair, and that all motor parameters were nominal and within manufactures tolerances. We recorded the following:

• Resistance
• Meg-Ohm
• Surge
• DC continuous ramped
• Step-voltage
• Polarization index (PI)
• Dielectric analysis

The motor had been received to JJ Loughran in working condition, so it was decided, having confirmed the motor had passed all electrical parameters, to run the unit in question on our Variable speed drive test bed – starting from a Low Hertz level and then running the unit up to full speed. The vibration levels would then be investigated.

Full vibration readings were taken for the Drive End and Non-Drive End bearings, they did not meet the following JJ Loughran requirements as stated below: –

Nominal Bearing test Between

• Velocity Test = 4.5mm/Sec -7.5mm/Sec
• Acceleration Test 1.0g-2.5g

The two types of vector quantities that were measured were as follows: –

VELOCITY (mm/s units) – Measures the machine forces related to movement of the rotating centre lines. This indicates issues such as looseness, unbalance, bent shafts etc. Velocity is the rate of change of position with respect to time

ACCELERATION (‘g’ units) – this is used to indicate high frequency vibration. This is used to identify bearing defects, lubrication, gearbox issues and motor electrical faults etc. acceleration is the rate of change of velocity.

The velocity levels measured on the 150KW Brook motor were found to be above the ISO 10816 alarm levels.  Further to these test results JJ Loughran engineers removed the end housing for inspection and found there was excessive wear.

Further to our investigation, JJ Loughran overhauled the motor this work included:-

• Dismantle & strip motor
• Clean and strip stator
• Check balance of rotor using inhouse test equipment.
• Repair Terminal on terminal block
• Mechanically repair housings
• Replace bearings with SKF bearings including an insulated bearing on the NDE
• Reassemble & run on drive
• Clean & deliver back to customer

After our machining department mechanically repaired the end housing and checked all mechanical tolerances. JJ Loughran engineers then rebuilt the motor and carried out all functional tests, which included full vibration checks for the drive end and non-drive end bearings.

The results (which had substantially lower Velocity & Acceleration readings from our initial test run) helped detail the successful repair of the Crusher Motor in question. All results were recorded using our IRD Model 258 Series

It is not always cost effective/sustainable to replace all electric motors; hence JJ Loughran engineering workshop is crucial in ensuring that all customers are supported in the most effective and ethical way possible.

JJ Loughran stock a large range of electric motor spare parts, including SKF bearings, seals, terminal blocks, rewind copper etc. We also have a machining department which can manufacture new shafts, coupling, fans and other critical electric motor parts as required, thus enabling our engineers to carry out quick turnarounds on mission critical pieces of equipment.