Motors and Variable Frequency Drives

There are many different options and recommendations on what motors and VFD’s to use on a 2×72 Belt Grinder.  We have put together a simplified version of recommend options to use on the Nexus Grinders.  This by no means are the only options for motors or VFD’s.  Do your research and become informed on what is needed to power and control a 2×72 belt grinder.

The key factor for determining what size motor and/or VFD to use will depend on what power you have available in your shop or garage.
If you only have 115 volt supply, you will be looking at using 1.0 to 1.5 horsepower motors.
If you have 230 volt supply, you will be looking at using 1, 1.5, and 2.0 horsepower motors.  You can go with larger horsepower motors, but you will need a larger rated VFD which will increase costs.

Motors
If you use a 56C frame motor with a foot mount, you can use the C face mount for the NG-3. With the foot mount you can also use it for NG-2 model.  Most motors now days offer both a C face and a foot mount.  If you don’t have one or can’t find one, make sure you obtain the correct motor mount for the Grinder. Nexus Grinders sells motors for the NG-3 and NG-2

You want to use Total Enclosed Fan Cool (TEFC) motors. Open motors are a poor choice, as grinding dust will get inside of the motor and it will eventually fail.
If you are using a 4” or 5″ drive wheel, you will want a 3600 rpm motor.
You should also look for motors that are electronically reversible.
If you are using a VFD, you will need a 3-phase motor. (see VFD notes below).
If you want to use a counter shaft with pillow blocks, sheaves (pulleys) and belt, you can use a 1.5 or 2.0 horsepower, single phase motor. You can only use this type of setup with the NG-2 models.

Variable Frequency Drives
Variable Frequency Drives are commonly referred to VFD’s.
If you want to use a VFD, you need to use a 3-phase motor.
VFD’s convert single phase 115 or 230 volt inputs into 3-phase outputs to the motor.
You can’t use a single-phase motor on the industry standard VFD’s that most knife makers use for grinders.
VFD’s control speed and some may also allow you to use forward and reverse settings.
You can’t use a motor that is rated higher than the VFD rating. You can use a higher rated VFD with a lower rated motor. So you can use a 2.0 horsepower VFD with a 1.0 to 2.0 horsepower 3 phase motors.  You should not use a 3.0 horsepower motor with a 2.0 horsepower rated VFD.

There are many manufactures of VFD’s, so look for a VFD with a NEMA 4-X protection rating which is sealed from dust, water and a corrosion resistant exterior. If you use a VFD with NEMA 1 rating, you will need to protect the drive and provide a fan and filter to keep the drive cool and to not allow grinding dust to penetrate your VFD.  In the end, it’s not much more money and definitely worth your time to buy a NEMA 4-X rated VFD.

KB Electronics sells many models of VFD’s.  You can buy KBAC drives from Nexus Grinders in Canada who is an authorized distributor.

If you purchase the KBAC-27D model, you can use the VFD with the 115 and 230 volt inputs and can use 1.0 horsepower, 1.5 horsepower and 2.0 horse power, 3-phase motors.

The 115 volt input you can use a 1.0 or 1.5 (maximum) horsepower, 3-phase motor.
The 230 volt input you can use a 1.0, 1.5. or 2.0 horsepower, 3-phase motor.

AC line input 115 volts, maximum current 22 amps, and a 25 amp circuit breaker.
AC line input 230 volts, maximum current 16.7 amps, and a 20 amp circuit breaker. Make sure you have the required power supply and circuits available. See Table 2 on page 7 kbac_manual

If you use the KBAC-24D model you are limited to a maximum of 1.0 horsepower, 3-phase motor.
AC line input 115 volts, maximum current is 14.4 amps and a 20 amp circuit breaker. Make sure you have the required power supply and circuit available.

The KBAC VFD’s are rated NEMA 4-X. You can also add an optional forward and reverse switch along with a line switch that will allow you to turn the power off to the drive.

Recommendations:
Now that you have learned a lot about motors and VFD’s. Here are some recommendations we have put together to assist you in making your decision.

Option 1
1.5 horsepower or 2.0 horsepower, 230 volt, 3-phase motor.
56C or 56HC flange Mount
Electronically reversible
TEFC (Total Enclosed Fan Cooled)
3600 rpm (use with 4”or 5″ Drive Wheel)
Variable Frequency Drive (VFD) KBAC 27D 230 volt single-phase input (rated up to 2 hp)

Option 2
1.0 to 1.5 horsepower, 230 volt, 3-phase motor.
56C or 56HC flange Mount
Electronically reversible
TEFC (Total Enclosed Fan Cooled)
3600 rpm (use with 4” or 5″ Drive Wheel)
Variable Frequency Drive (VFD) KBAC 27D 115 volt single-phase input (rated up to 1.5 hp)

Option 3
1.0 horsepower, 230 volt, 3-phase motor.
56C or 56HC flange Mount
Electronically reversible
TEFC (Total Enclosed Fan Cooled)
3600 rpm (use with 4” or 5″ Drive Wheel)
Variable Frequency Drive (VFD) KBAC 24D 115 volt single-phase input (rated up to 1 hp).

Option 4
1.5 horsepower, 115 volt, single-phase motor.
56C or 56HC flange Mount
Electronically reversible
TEFC (Total Enclosed Fan Cooled)
3600 rpm (use with 4” or 5″ Drive Wheel)
Counter-shaft, with pulleys and belt or as a direct motor mount on the NG-3

Nexus Grinders sells 1hp, 1.5hp and 2hp three phase motors for your convenience. We can also obtain single phase motors too.

eMotors Direct is a Canadian Distributor with operations across Canada. Their prices are very competitive and they generally have flat rate shipping on motors.  eMotors Direct  or 1-800-890-7593

For KBAC drives, please review the manual available at KB Electronics. You can also contact Nexus Grinders who is an authorized re-seller for information on KB Electronics VFD’s.   https://www.kbelectronics.com

Warning:
Working on electrical circuits or incorrectly connecting electrical equipment can be extremely hazardous. Please consult with qualified electrician and qualified personnel if you are unsure how to make safe electrical connections.  Electrical connections should meet or exceed National, Provincial, and local electrical codes. Always refer to the manufacture’s manuals and installation instructions. You may need permits if you are making changes or adding circuits to your electrical panel. Please check with your local authorities before starting any electrical connections.