Permanent Magnet Motors
Superior motor efficiency helps reduce electrical power cost by up to 20%
Borets was the first company in the world to commercialize the permanent magnet motor (PMM) for ESP downhole applications back in 2006. Since then, Borets has deployed more than 14,500 PMMs around the world serving a variety of ESP and PCP applications.
Permanent magnets – specially engineered and embedded in the rotor – create a constant rotor magnetic field. No electrical power is consumed in generating the rotor magnetic field. As a result the PMM rotor experiences little to no electrical losses, is more efficient, and has higher horsepower density. This translates to a synchronous PMM with wide operating range that consumes less energy, generates less heat, and is shorter in length than an induction motor of the same rating.
Compared directly to an equivalent horsepower induction motor, PMMs have been shown to reduce power consumption by about 7 – 10 % at best efficiency point (BEP). Energy savings up to 20% or more are achievable using PMMs when the motor and system operate in frequent or prolonged underload conditions – or not at BEP.
Using a proprietary vector control algorithm, Borets variable speed drives (VSDs) control and optimize motor current across the full range of motor loads encountered, constantly minimizing electrical power consumed.
Dedicated engineering effort combined with almost 20 years of practice have resulted in the largest proven portfolio of PMMs available to the industry. Sizes and power ratings of available Borets PMMs are summarized in the table.
|Available Speeds (rpm)||6000||3600, 6000||500, 3600||3600||500, 3600|
|Motor Efficiency||Up to 93%||Up to 93%||Up to 93%||Up to 93%||Up to 93%|
|Rated Winding Temp (C) [F]||200 ||200 ||200 ||200 ||200 |
All Borets PMMs are single section motors with a wide range of horsepower available in each series size.
Permanent Magnet Motors
- Artificial lift using
- Electric submersible centrifugal pumps
- Electric submersible progressing
- Lower ESP operating expense through reduced power consumption
- Lower motor heat rise improves equipment longevity and run life
- Reduced equipment string length for
- Deeper pump setting depths
- Improved wellbore access through doglegs
- Available in 319, 406, 456, 512, and 562 series sizes
- Wide operating speed range:
- Low-speed PMM: 120 – 1,500 rpm
- Standard-speed PMM: 500 – 3,900 rpm
- High-speed PMM: 3,000 – 6,000 rpm
- Motor effi ciency up to:
- Low-speed PMM – 83%
- Standard-speed PMM – 93%
- High-speed PMM – 93%
- High power factor (very close to 1)
- No rotor slip
- Locked rotor bearing design
PMM Operating Principle
Permanent magnets made of sintered hard-magnetic materials are incorporated into the design of the PMM rotor. It is the rotor flux produced by these magnets that interacts with the stator magnetic field to produce motor torque. Power consumption and heat rise are both reduced since no current is induced in the PMM rotor.
PMM vs. IM Advantages
Results of field test comparisons of PMM to IM performance conducted by Borets and lab testing conducted by five major operators are summarized
in the graphic. The tests confirmed the superior performance of PMMs, including better efficiency, higher power factor, and 15% average energy savings.
The proven technology of permanent magnet motors (PMMs) has shown to reduce operating expenses attributable to ESP power consumption up to 20% or more. PMMs also experience lower heat rise than an equivalent horsepower (HP) induction motor (IM) contributing to improved reliability and
longer run life. The higher HP rotor density means PMMs are also significantly shorter than an IM equivalent, which enables deeper pump setting depths as well as facilitating better clearance through severe doglegs or tortuous well paths.
Borets PMM performance is optimized using a proprietary vector control algorithm in the surface variable speed drive (VSD). Key motor performance characteristics – determined under a controlled lab tuning process – are uploaded to the control algorithm enabling the VSD to optimize motor power consumption and control stability uniformly across the full spectrum of motor load variation.
Borets has the industry’s largest portfolio of proven PMMs across a range of series size and ranging from low-speed (120 rpm) to high-speed (6,000 rpm) in support of standard (PMM-ESP), high-speed (Slimline and WR2) and low-speed (PMM-PCP) applications. All Borets PMMs come as single section motors.
As the global leader in PMM technology development and experience, Borets first introduced PMM technology in 2006 and has since deployed more than 14,800 PMMs worldwide. The maximum recorded PMM run life is 2,708 days.
Available PMM Sizes and Horsepower Range