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 1.5 to 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-lll and with the foot mount you could use it for the NG-l and NG-ll grinders.  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. Automation Direct in the USA has free shipping to Canada and their prices are good. There are many other suppliers in Canada and the USA, so please shop around.

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” 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 horsepower, single phase motor. You can only use this type of setup with the NG-l and NG-ll models.

Variable Frequency Drives
Variable Frequency Drives are commonly referred to VFD’s.
If you want to use a VFD, you must 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 a VFD.
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 in the USA and Canada.
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.

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” Direct 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” Direct Drive Wheel)
Variable Frequency Drive (VFD) KBAC 27D 115 volt single-phase input (rated up to 2 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” Direct 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” Drive Wheel)
Counter-shaft, with pulleys and belt

Enclosed is some information on motors from Automation Direct

1 hp 1-phase
IronHorse standard performance AC induction motor, general purpose, 1hp, 1-phase, 115/230 VAC, 3600rpm, TEFC, 56C frame, rolled steel, rigid base/C-face mount.MTR2-001-1AB36

1.5 hp 1-phase
IronHorse standard performance AC induction motor, general purpose, 1-1/2hp, 1-phase, 115/230 VAC, 3600rpm, TEFC, 56C frame, rolled steel, rigid base/C-face mount.MTR2-1P5-1AB36

2.0 hp 1-phase
IronHorse standard performance AC induction motor, general purpose, 2hp, 1-phase, 115/230 VAC, 3600rpm, TEFC, 56HC frame, rolled steel, rigid base/C-face mount.MTR2-002-1AB36

1.0 hp 3-phase (use KBAC24D or KBAC27D
IronHorse premium efficiency AC induction motor, general purpose, 1hp, 3-phase, 208-230/460 VAC, 3600rpm, TEFC, 56C/HC frame, rolled steel, rigid base/C-face mount.MTRP-001-3BD36

1.5 hp 3-phase (use KBAC27D)
IronHorse premium efficiency AC induction motor, general purpose, 1-1/2hp, 3-phase, 208-230/460 VAC, 3600rpm, TEFC, 56C/HC frame, rolled steel, rigid base/C-face mount.MTRP-1P5-3BD36

2.0 hp 3-phase (use KBAC27D)
IronHorse premium efficiency AC induction motor, general purpose, 2hp, 3-phase, 208-230/460 VAC, 3600rpm, TEFC, 56C/HC frame, rolled steel, rigid base/C-face mount.MTRP-002-3BD36 

3.0 hp 3-phase (use KBAC29(1P))
IronHorse premium efficiency AC induction motor, general purpose, 3hp, 3-phase, 208-230/460 VAC, 3600rpm, TEFC, 56C/HC frame, rolled steel, rigid base/C-face mount.MTRP-003-3BD36

References:
Note: Nexus Grinders has no affiliations with KB Electronics or Automation Direct.  These are provided as examples and a starting point for your research.

For KBAC drives, please review the manual available at KB Electronics or call them at 1-888-637-7333. https://www.kbelectronics.com
For Automation Direct motors, please review the manual available on their website or phone 1-800-633-0405. https://www.automationdirect.com

There are many suppliers for motors and VFD’s.  Please research and shop around for what best suits your needs.

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.