Learn About Residential Motors Available in Hagerstown Maryland

Single Phase Motors

Single phase electric motors are a major contributor to our comfort and conveniences in the retail market and our homes. While they are not used as heavily in the industrial and commercial markets, that doesn't mean they aren't used at all... just not as much as the retail and residential markets. And that is primarily due to the fact that "Single Phase Power" is the sole electrical system available to 99% of the residential market, while "Three Phase Power" is the system available to the majority of the commercial/industrial markets. So the use of Single Phase Motors has more to do with available power sources than anything else.

By and large, the selection of Single Phase Motors available, from which to make our selections, is certainly limited, compared to that available in the three-phase market. And this has to do with the market that needs to be served and the efficiency of three-phase power compared to single-phase power. In the chart below, you can compare the various single-phase motor types with respect to HP, starting torque, starting current, efficiency and application. This should certainly give you an idea of why you should use a certain type and how it will benefit you when you do.

Single Phase Motor Operating Characteristics
Type	Size - HP	Start Torque	Start Current	Applications	Efficiency
Split-Phase	1/20 - 1/2 HP	Low	High	fans, blowers, centrifugal pumps, washing machine, grinder, lathes, air conditioning and furnace fans	Low
Capacitor Start-Induction Run	1/3 to 10 HP	High	High	conveyors, grinder, air conditioners, compressor	Moderate
Capacitor Start-Capacitor Run	1/3 to 10 HP	High	High	conveyors, air conditioners, compressors, agricultural industry silo unloaders	High
Permanent Split Capacitor	1/20 to 3/4 HP	Low	Moderate	fans and blowers in heaters and air conditioners condenser fans	High
Shaded Pole	1/300 - 1/20 HP	Very low	Low	small instruments, hair dryers, toys, record players, small fans, electric clocks	Low
Universal	to 2500 Watts	Low	Moderate	Home appliances and power tools.	Low
Repulsion Start-Induction Run	1/2 to 40 HP	Very high	Moderate	Planers, wood working machines, silo unloaders, refrigeration compressors	Moderate

There are a number of options available for these Single Phase motors that are dependent on actual application needs. The majority of the motors are available in a variety of mounting types, enclosure options and shaft arrangements.

For instance, enclosure options may include: ODP (Open Drip Proof), TEAO (Totally Enclosed Air Over), TENV (Totally Enclosed Non-Ventilated, and TEFC (Totally Enclosed Fan Cooled). For mounting types, the list includes: rigid base mounted, resilient base mounted, resilient ring (only), through-bolt mounted, "belly-band" mounted, pedestal mounted, and probably some additional options that are not quite so common. And here's an additional point to keep in mind with one of the specific enclosure types; i.e. TEAO (Totally Enclosed Air Over). This motor is DESIGNED to have the process air (the air that is being moved) pass over the motor to act as "cooling" air. If you put this type of motor in an application where the motor sits "outside" the air flow, the motor is going to burn up, since it doesn't have sufficient cooling air.

When it comes to the shaft options, they too vary with application and frame size. For instance, some motors may have a base with mounting holes punched for 48 and 56 frame mounting, but the motor shaft will be 1/2" with a "flat". Then there are motors with a "double ended shaft" for mounting 2 squirrel cage fans. While a normal shaft length of a motor may be 2-1/2" or 3" long, some PSC or other motors may have a shaft that is 8" long or more to accommodate the length necessary to mount the condenser fan when used in an outdoor heat pump. So make certain you KNOW what diameter shaft you need and what length it has to be for your application.

And a final note, direction of rotation... You've got to get this right! Some designs of motors, specifically PSC, are usually designed with a simple "plug and jack" assembly that you un-plug, turn it 180°, and reinsert the plug to reverse the direction of rotation. Others have extra electrical connecting pins on the terminal board where you connect the incoming power. In this type, you need to move a specific wire from an original position to this other pin to reverse directions. And then the REAL issue...! Motors that are simply NON-REVERSIBLE. With these motors you MUST know what direction you need the motor to turn when it is purchased. Having difficulty understanding the direction of rotation? Here's a "rotational" definition taken from a Siemens Product Support website:

In accordance with DIN EN 60034-8, the direction of rotation of a motor is defined as follows:

• The direction of rotation is the direction viewed from the drive end.
  • This means looking into the "drive" end of the shaft.


• The drive end is the side with the shaft extension.
  • For machines with two shaft extensions, the drive end is:
    • a) the end with the bigger shaft diameter
      b) the end on the opposite side to the fan,
      • if both shaft extensions have the same diameter.


• Clockwise Rotation
  • Turn the shaft clockwise when viewed from the drive end.
  • Viewing direction is from drive end to non-drive end.


• Counter-Clockwise Rotation
  • Turn the shaft counter-clockwise when viewed from the drive end.
  • Viewing direction is from drive end to non-drive end.

Types of Single Phase Motors

Split Phase

Split phase motors have a starting switch but no capacitor or additional starting mechanism. Their starting winding is simply electrically offset from the running winding by an amount sufficient to begin the rotating member in a specific direction. Because there is no "additional" starting assistance, this motor has moderate to low starting torque.... in the range of 100% to 125% of full load torque. In addition, the starting current will be rather high. Motors of this type are used on applications that are relatively easy to start but may build power requirements as the rotational speed increases.

Typical applications are belt driven fan loads and some pump applications.

Capacitor Start-Induction Run

This is a real "work horse" of the single-phase line of motors. These motors incorporate a starting winding, starting switch and electrolytic capacitor. When the motor is asked to start, the capacitor discharges into the start winding giving it a "shot in the arm" to get it going. Then, as in other single-phase motors with starting switches, when the rotor reaches approximately 75% to 80% of full speed, the starting switch OPENS, removing the capacitor and start winding from the circuit and allows the MAIN or running winding to complete the ramp up of speed to full operational RPM.

These motors can be manufactured with moderate to high starting torque, based heavily on the capacitor rating and start winding design. The motor will also have high breakdown torque which keeps the motor "locked" into it's running speed even with high overloads. These motors with MODERATE starting torques of 175% or less are typically used on fans, blowers, and pumps. The high starting torque motors.... used on loads requiring up to and above 300% full load torque to start, can be used on compressors, and industrial, commercial and farm equipment. In the agricultural market, applications such as silo un-loaders and other "hard to start" loads are a natural for these devices. 

Capacitor Start-Capacitor Run

 

These motors parallel the design and application of the Capacitor Start motor identified above, except that they have an oil filled, RUNNING capacitor in the circuit with the MAIN or running winding. This capacitor stays in the circuit ALL THE TIME and helps improve the running efficiency and lowers the full load running current. These motors are typically in the higher single-phase horsepower ratings... above 2 HP, with the agricultural industry being a major user of these motors.

Permanent Split Capacitor

              

Motors of this type are used in many of the same applications as the shaded pole motor. The major differences are that the PSC motor has much higher efficiency, lower running current (50% - 60% less), and higher output power capability. The PSC motor gets it's name from the fact that there is a "RUN" capacitor connected in the motor circuit at all times. This device assists in maintaining a high efficiency and power factor, and decreasing the amount of power consumed for the same power output. These motors can be used to replace ANY shaded pole motor except those where the physical size of the PSC will not fit.... i.e. a clock motor or small evaporator cooling fan. The output power of a PSC motor will be in the range of "sub-fractional HP" i.e. 1/20 HP to a maximum of 3/4 HP. Single speed or multi-speed motors can be designed with the top speed being 1625 RPM and the 1075 RPM being the most popular speed. Multiple speeds in one motor are accomplished either by "tapping" the winding or a "choke" coil.  Starting torque on this motor type is also considered LOW.

Shaded Pole

         

These motors have low starting torque, low efficiency, medium high running current, low power characteristics, no capacitors, no starting switch and are low cost. Motors of this type are found on small direct drive furnace blowers, window fans and other fan applications found in the residential community. Shaded pole motors should NOT be used to replace OTHER TYPES of single-phase motors, mostly due to the low torque and efficiency. Motors of this type are also used in small appliances and items such as bathroom exhaust fans, clock motors, and evaporator fans on refrigerators and freezers.

Although low in efficiency, with low starting torque, because of the inherent LOW COST, these motors abound in the proper residential applications. The output capability of a shaded pole motor will range from "sub-fractional HP" i.e. 1/30 HP to a maximum of 1/4 or 1/3 HP. Speeds will commonly be 2 pole (3000 RPM), 4 pole (1550 RPM) and 6 pole (1050 RPM).

Universal Motor

The universal motor is a type of electric motor that can operate on either AC or DC power and uses an electromagnet as its stator to create its magnetic field. It is a commutated series-wound motor where the stator's field coils are connected in series with the rotor windings through a commutator. It is often referred to as an AC series motor. The universal motor is very similar to a DC series motor in construction, but is modified slightly to allow the motor to operate properly on AC power. This type of electric motor can operate well on AC because the current in both the field coils and the armature (and the resultant magnetic fields) will alternate (reverse polarity) synchronously with the supply. Hence the resulting mechanical force will occur in a consistent direction of rotation, independent of the direction of applied voltage, but determined by the commutator and polarity of the field coils.

Universal motors have high starting torque, can run at high speed, and are lightweight and compact. They are commonly used in portable power tools and equipment, as well as many household appliances. They're also relatively easy to control, electromechanically using tapped coils, or electronically. However, the commutator has brushes that wear, so they are much less often used for equipment that is in continuous use. In addition, partly because of the commutator, universal motors are typically very noisy, both acoustically and electromagnetically.

Repulsion Start-Induction Run Motor

While this motor is mentioned here, we consider it more of a "Special" motor and it can be found in more detail on that topic page. Click here to be taken to the Special Motor page of our website.

We hope you've been somewhat enlightened with the information offered on these typical Single Phase motors. As always, you can talk to our application folks by phone or email for additional information. Click this link to obtain the phone numbers and/or email addresses of our team.