A.O. Smith ST1302 Manual
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A.O. Smith ST1302 Manual

Pump motors
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A.O. SMITH
A.O. SMITH
A.O. SMITH
A.O. SMITH
A.O. SMITH
A.O.Smith
Motor
Master y
University
PUMP
MOTORS
APPLICATION
INCLUDES:
SWIMMING POOLS
SPA & JETTED TUB
JET PUMPS
INSTALLATION TIPS
REPAIR
TROUBLESHOOTING
OTHER MODULES INCLUDE:
HEATING, VENTILATION,
AIR CONDITIONING &
REFRIGERATION MOTORS
GENERAL PURPOSE MOTORS
SPECIAL PURPOSE MOTORS

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  • Page 1 PUMP A.O. SMITH A.O. SMITH A.O. SMITH A.O. SMITH A.O. SMITH MOTORS A.O.Smith APPLICATION Motor INCLUDES: SWIMMING POOLS Master y SPA & JETTED TUB JET PUMPS University INSTALLATION TIPS REPAIR TROUBLESHOOTING OTHER MODULES INCLUDE: HEATING, VENTILATION, AIR CONDITIONING &...

  • Page 2: Table Of Contents

    2-Speed Motors Hi-Low Switch Reconnection ....... . .46 © 2001 A.O. Smith Corporation...

  • Page 3: Introduction

    Pump Motors Introduction The motors discussed in this application mod- ule are those commonly found on swimming pools, spas, jetted tubs, home water systems and other centrifugal pumps. The motors are 48 and 56 frame used to pump water. MOTOR TYPES There are five distinct electrical designs which may be found on some or all of the pumps being discussed.
  • Page 4 5. Polyphase (3 Phase) This is the simplest, most efficient design. Its use is limited to commercial and industri- ST1302 CAP START/RUN al applications since three phase power is not available in residential areas. These same motors may sometimes be applied...
  • Page 5 Pump Motors The overloads or protectors used on pump motors are tested on an eighteen day locked cycle test. The eighteen days simulates a two week vacation plus weekends and a couple of extra days. During the test, the motor shaft is locked and power is applied to the motor.
  • Page 6 Pump Motors The principle of operation can be demonstrated by a whirling bucket of water. As the bucket is rotated (figure 1), the water is held in the bucket by centrifugal force. If we were to punch a hole in the bottom of the bucket, the water would be forced out, again by centrifugal force (figure 2).
  • Page 7 Pump Motors An open impeller puts a great deal more force on the motor bearings than does the closed impeller. A 203 bearing is often used with closed impeller pumps while open impeller may require a larger 304 bearing on shaft end. Closed impeller pumps are used extensively today.

  • Page 8: Motor Replacement

    Pump Motors REPLACEMENT MOTOR SELECTION Replacement The nameplate on the motor being replaced contains much of the critical information needed Motor to select a new motor. Some of the nameplate data detailed in the Replacement Module is Selection repeated below in order to reemphasize its impor- tance to the application.

  • Page 9: Swimming Pool, Spa And Jetted Tub Motors

    Pump Motors SWIMMING POOL, SPA Swimming AND JETTED TUB MOTORS Applications include in-ground pools, above Pool, Spa and ground pools and pool cleaners. Jetted Tub There are no efficiency standards for single Motor s phase motors. Motors designated high efficiency by a motor manufacturer are just more efficient than their standard motors.
  • Page 10 Pump Motors In the past when brass pumps were common, the use of motors with cast iron instead of alu- minum end frames was common. The cast iron has less reaction with the brass. Today, most pumps are plastic so this is not a concern. Small above ground pumps have a sealed SK1072 motor/pump unit which is not repairable.
  • Page 11 Pump Motors Pool sweep pumps may use motors with special flanges and shaft extensions. These are specifi- cally identified in motor manufacturers’ catalogs. Running a pump dry does not harm the motor which is actually operating at a very light load. However, if the seal is damaged by the dry oper- SPS1052 ating condition, it will leak and probably allow...

  • Page 12: Voltage

    Pump Motors VOLTAGE Voltage Most dual voltage (115/230V) motors are con- nected at the factory for 230 volts for two rea- sons. First, the highest percentage of motors are installed on the higher voltage. Second, if a motor is connected for 230 volts and 115 volts are applied in the field, the motor will hum and trip the overload.

  • Page 13: Service Factor

    Pump Motors SERVICE FACTOR Service Typical service factors for full rated one horse- power pool pump motors are 1.65 for square Factor flange and 1.4 for NEMA C. One horsepower jet pump motors typically have a 1.4 service factor. Over the years, various amp ratings have been used on motor nameplates.
  • Page 14 Pump Motors The following chart illustrates the important fact of comparing total or maximum horsepower: High Service Low Service Factor Motor Factor Motor NEMA F.L. Std. Motor F.L. Up-Rated MAX HP MAX HP Uprated 1.75 1.16 Uprated 1.60 1.07 Uprated 1.50 1.13 1.13...

  • Page 15: Jet Pumps

    Pump Motors JET PUMPS Jet Pumps The two most popular types of home water sys- tems have their water delivered and pressure developed by either a jet pump or submersible pump. As the name implies, the submersible pump/motor unit is located in the water supply and connected to a waterproof electrical supply.
  • Page 16 Pump Motors Most jet pumps use NEMA C face (56C or 56J) or square flange motors. Most square flange motors have 1/2-20 threads but some have 7/16- 20 threads. Many other centrifugal pump appli- cations such as lawn sprinklers and irrigation use jet pump type motors.
  • Page 17 Pump Motors One way of visualizing the action is comparing it to drinking from a straw. The partial vacuum created when you suck on the straw causes the drink to be forced up the straw by air pressure. If the container from which you were attempting to drink were sealed, liquid would not be drawn into and up the straw.
  • Page 18 Pump Motors DIAPHRAGM A check valve or foot valve is normally located PRESSURE TANK in the plumbing line before the pump. This “one 30 PSI CUT IN way” valve is needed so that the pressure in the 50 PSI CUT OUT system will not bleed off when the pump stops.
  • Page 19 Pump Motors The primary function of the pressure tank is to protect the pump motor. Without a tank, pres- sure in the system would drop to zero almost immediately when a faucet was opened. Then, almost as quickly, the cut out pressure would be reached and the pump would shut off.
  • Page 20 Pump Motors When running at shut off the energy is convert- ed to heat. The water in the pump casing can boil under pressure to the point where a plastic impeller is melted. Some of the heat goes into the motor shaft and back to the bearing causing possible failure.

  • Page 21: Motor Troubleshooting Guide

    It can also vary with the total load on the power company grid. While some of the troubleshooting procedures that follow apply specifically to the two compart- ment A.O. Smith pump motor, the basics apply to other motors. Level 2 A.O.Smith...

  • Page 22: Recommended Wire Size

    Pump Motors See that this electrical list is followed: Assure proper voltage at motor terminals. Follow motor connection diagram on motor nameplate. Make sure motor is properly GROUNDED and complies with local and national electrical codes. See that the pump turns freely before starting motor. FAILURE TO START (MOTOR MAKES NO SOUND) Check voltage at motor line terminals.

  • Page 23: Overheating

    Pump Motors FAILURE TO START (MOTOR HUMS OR ATTEMPTS TO START) Check voltage at motor line terminals. If voltage is inadequate to start motor, check for loose connections, undersized wiring, over- loaded circuit or other causes of voltage drop. Start switch contacts not closed when motor is not operating.
  • Page 24 Pump Motors Overvoltage. This needs correction by the power company. High ambient temperature. Pool motors are normally designed to operate in higher ambi- ents (50˚C) than jet pump motor which usual- ly have short duty cycles. Artificially high ambients may be created if the motor oper- ates in a confined space and recirculates the air.

  • Page 25: Noisy Operation

    Pump Motors Check motor windings and capacitor (where used) for “ground” or “short”. Check terminal board connections with the motor wiring diagram for proper applied volt- age. Check the motor start switch and governor to be sure it is adjusted properly and is opera- tional.

  • Page 26: Protect Against Dirt & Chemicals

    Pump Motors Locate motor on a slight elevation so water will not run or puddle nearby. Avoid spilling or dripping liquid chemicals on or near the motor. Avoid splashing water on or near the motor. Repair leaky pipe joints, “O” rings, or pump seals promptly.

  • Page 27: Conventional Multimeter Or Ohmmeter

    Pump Motors CONVENTIONAL MULTIMETER OR OHMMETER An ohmmeter can be used to measure the resis- tance of the various motor windings as well as to test the insulation. The ohmmeter will have numerous ranges from R x 1 where the meter reads directly in ohms to an Rx100K where the actual meter reading must be multiplied by 100,000 for the actual ohm value.

  • Page 28: Voltage Check

    Pump Motors VOLTAGE CHECK Disconnect power source Remove canopy Determine motor voltage and set meter on proper scale Reconnect power Start motor Touch one probe to L1 and the other to L2. Voltage reading to be within 10% of nameplate voltage, i.e.

  • Page 29: Start Switch Check

    Pump Motors START SWITCH CHECK Visual checks: • Disconnect power source. • Remove canopy. Make sure there are no obstructions preventing the proper operation of the rotating governor. Check wiring and make sure none of the leads are in the area of the governor where they can be cut or interfere with the governor.
  • Page 30 Pump Motors Most newer models use only one screw to secure and adjust the switch. When a new switch is installed, or an existing switch is being reinstalled, the "U" bracket should be opened slightly to insure sufficient tension against the screw. Tighten only when adjust- ing.

  • Page 31: Motor Component Checks

    Pump Motors MOTOR COMPONENT CHECKS Based on your observations perform the follow- ing checks to confirm that each component is functioning properly. GROUND CHECK Ground Check — Set ohmmeter to R x 1K. Attach one probe to ground screw and touch other probe to all terminals on terminal board, switch, capacitor and protector.

  • Page 32: Winding Continuity

    Pump Motors WINDING CONTINUITY (For typical single phase, dual voltage only, capaci- tor start, single speed motor, connected for 230V. Set meter to R x 1). For single voltage motors, check between L1 and Slip a heavy piece of paper between points, taking care not to bend tabs.

  • Page 33: Capacitor

    Pump Motors CAPACITOR Capacitor — Set ohmmeter at R x 1K. Slip a heavy piece of paper between points. Discharge capacitor by touching the two termi- nals with the blade of an insulated handle screw- driver. Attach one probe to each terminal; ohmmeter needle should move rapidly to right then slowly drift to the left.

  • Page 34: Protector (Thermal Overload)

    Pump Motors NOTE: Motor cycling PROTECTOR (THERMAL OVERLOAD) on overload indicates Protector — Set ohmmeter to R x 1. some other problem, not Resistance between protector terminals: just a defective over- 1 & 2 should be approximately 0 (Disc.). load. 2 &...

  • Page 35: Single Speed Motor - Typical Schematic Diagrams

    Pump Motors SINGLE SPEED MOTOR — TYPICAL SCHEMATIC DIAGRAMS Capacitor Start Induction Run — Single Speed EXT. & WIRE ROUTING Dual Voltage — Single Speed — Capacitor Start With Voltage Change Plug Level 2 A.O.Smith...
  • Page 36 Pump Motors Capacitor Start Capacitor Run — Single Speed SWITCH RUN. CAP. Level 2 A.O.Smith...
  • Page 37 Pump Motors SINGLE SPEED MOTOR — TYPICAL SCHEMATIC DIAGRAMS Capacitor Start* or Split Phase Single Voltage on Winding Protector SWITCH *Capacitor not shown in schematic. Level 2 A.O.Smith...

  • Page 38: Motor Assembly

    Pump Motors MOTOR ASSEMBLY All of the motors covered by this manual are similar in design and construction, with varia- tions in baffles, type of protector, type of flange, and bearing construction. When disassembling, make sure you note the exact location of all com- ponents so they can be reassembled in the proper order.

  • Page 39: How To Replace Bearings

    Pump Motors HOW TO REPLACE BEARINGS LONG SHAFT END 1. Remove the bearing(s) from the BEARING motor shaft following these steps LOCK PLATE as necessary: SHIELD Use an external ring pliers to remove snap rings which are RING used to secure bearings. Use a bearing puller to remove defective bearing(s).
  • Page 40 Pump Motors • Opposite end: Place the long end of the shaft on the wood block. Place the bear- ing (and other parts as used, such as snap rings and washers) over the short end of the shaft. Tap the bearing into place using the proper size tube and a mallet, or use a press.

  • Page 41: Bearing Information Table

    Pump Motors BEARING INFORMATION TABLE Bearing Installation Tube Dimensions Bearing Dimensions (In Inches) A.O. Smith Bearing Bearing Width Size Diameter (Inches) Outer Wall Minimum Part No. Diameter Thickness Length (Inches) Inside Outside of Tube 202-16 .6299 1.3780 .4331 610358-1 .095 .6693...

  • Page 42: Motor Reassembly

    Pump Motors CAUTION: When MOTOR REASSEMBLY routing leads under the Reassemble the motor in reverse of the disas- canopy be sure that: sembly procedure. A. No leads are in the Observe all reassembly precautions and area of the rotating adjust the motor start switch. governor.

  • Page 43: Start Switch Replacement And Adjustment - 2-Speed Motors

    Pump Motors START SWITCH REPLACEMENT AND ADJUSTMENT — 2-SPEED MOTORS Proper starting switch adjustment on two-speed motors is essential for satisfactory operation and contact life. Disconnect all power to the motor before attempting any repair. Repair work should only be performed by a qualified electric motor technician. Fasten switch snugly to end bell, through “U”...

  • Page 44: Switch Connections High Speed Start

    Pump Motors SWITCH CONNECTIONS — HIGH SPEED START WHITE (COMMON) TOP VIEW START CAPACITOR YELLOW TO #5 (FROM START WINDING) YELLOW TO #1 TO #5 RED TRACER RED TO #2 BLACK TO #4 BLACK TO #3 (4 POLE MAIN) YELLOW TO #1 (2 POLE MAIN) TERMINAL #1 TERMINAL #2...

  • Page 45: Switch Connections Low Speed Start

    Pump Motors SWITCH CONNECTIONS — LOW SPEED START Low speed start — this design motor always starts on the low speed (4-pole) windings. When the control calls for high speed run, the start switch automatically switches the motor to high. WHITE (COMMON) TOPVIEW...

  • Page 46: 2-Speed Motors High Speed Schematic Diagram (Remote Switch Operation)

    Pump Motors 2-SPEED MOTORS — HIGH SPEED START SCHEMATIC DIAGRAM 2-Speed for Remote Switch Operation WHITE LINE VOLTS (LOW SPEED) BLACK LINE VOLTS BLACK (HIGH SPEED) START CAPACITOR YELLOW START - X & Y CLOSED Z OPEN RUN - X & Y OPEN Z CLOSED Level 2 A.O.Smith...

  • Page 47: 2-Speed Motors Hi-Low Switch Reconnection

    NOTE: Several different connections have been used in production. If the wiring on the motor you are reconnecting does not match these diagrams contact A.O. Smith and we will FAX or mail a connection for that model. RECONNECTION FOR REMOTE SWITCH OPERATION REMOVE BOTH YELLOW LEADS FROM ‘A’...

  • Page 48: 2-Speed Motors Hi-Low Switch Reconnection

    NOTE: Several different connections have been used in production. If the wiring on the motor you are reconnecting does not match these diagrams contact A.O. Smith and we will FAX or mail a connection for that model. RECONNECTION FOR REMOTE SWITCH OPERATION...
  • Page 49 Pump Motors MOTOR REPLACEMENT REMINDERS Motor A. If possible, isolate the cause of failure so that: Replacement 1. There will be confidence that a similar replacement motor will have an accept- Reminder s able service life. 2. If external conditions (moisture, low volt- age, etc.) contributed to the failure, they may be corrected.
  • Page 50 Pump Motors It may even lead to confusion. For exam- ple, some A.O. Smith pump motor model numbers begin with a letter: C = Capacitor Start, S = Split Phase, K = Capacitor Start and Run, P = Polyphase. The next two numbers designate the motor frame size: 48 = 48 Frame, 56 = 56 Frame.
  • Page 51 Pump Motors OPERATING REMINDERS Operating A. Locate the pump/motor in a clean, dust-free Reminder s area. Most pool and jet pump motors are open drip proof designs which circulate exter- nal air for cooling. Air contaminants such as sweeping dust and grass clippings may clog internal air passages leading to overheating.
  • Page 52 531 NORTH FOURTH STREET TIPP CITY, OH 45371 937) 667-6800 FAX: (937) 667-5873 www.aosmithmotors.com © 2001 A.O. Smith Corporation Bulletin #3300 3/01...

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