A: Should a motor be disassembled for any reason, the rotor end play must be adjusted. Use one of the following procedures, depending upon the type of thrust bearing:
zen supply professional and honest service.
1. Spherical Roller Thrust Bearings and Angular Contact Bearings (With Springs)
On spherical roller or angular contact thrust bearings with springs, setting the correct end play for preload requires a controlled assembly method, due to various deflections internal to the motor and friction of locknut threads from spring force. An end play setting of .005 to .008 inches is required to allow the lower guide bearing to return to an unload position when external thrust is applied to the motor (see Figure 5). End play can be properly adjusted by the following recommended procedure:
NOTE: Certain motor builds require removal of the fabricated steel or cast aluminum oil baffle to provide access for depth micrometer measurements.
Motors built with spherical roller thrust or angular contact bearings with springs require a minimum external thrust load, sufficient to compress upper die springs and unload lower guide bearing from axial spring thrust. Refer to the motor’s spring thrust plate for required minimum thrust.
NOTE: Do not run motor without load for more than fifteen minutes, as lower bearing damage may occur and improper seating of thrust bearing may cause vibration.
2. Angular Contact Ball Bearings (Without Springs)
No preliminary measurements are required to set end play. End play may be set by any of the following methods described in this section.
End Play Adjustment Methods
Method 1 (refer to Figures 6 & 7)
This method requires the user to install a bolted chain from the bearing mount back to a lifting lug, and rotate the locknut with a spanner wrench and 8 foot long bar until the dial indicator shows no movement on the end of the shaft. The locknut should then be loosened until .005 to .008 end play is obtained. Lock the locknut with the lockwasher. (See figure 7 for location of dial indicator.)
NOTE: This is the lowest cost of the three methods and requires the least amount of equipment. This method, however, may be less desirable than Method 2, as considerable locknut torque may be encountered on units with die springs.
Special equipment required includes:
Method 2 (refer to Figure 8 - Utilized on Spring Loaded Bearings Only)
This method utilizes a spreader bar and chains to wrap around lifting lugs, a hydraulic jack (five ton), and a crane to lift the spreader bar. The hydraulic jack is supported by two steel blocks of equal thickness on top of the bearing mounting, with the jack pushing against the spreader bar. On very heavy solid shaft rotors, the rotor can be lifted by placing a second jack below the motor to allow the locknut to be turned easily. After correct range (recorded earlier) is obtained, lock the locknut with the lock washer.
NOTE: This method utilizes usual shop equipment and tools. End play settings can be checked quickly on larger vertical motor products. The locknut lifts rotor weight only.
Special equipment required includes:
Method 3 (refer to Figure 9)
This method uses a one inch thick steel disc, with center hole for shaft end bolt, and two threaded hydraulic jacks connected to a single pump. Apply load to the hydraulic jack until the dial indicator shows no movement on the end of the shaft. (See figure 7 for location of dial indicator.) Pressure from the hydraulic jack should be relieved until .005 to .008 end play is obtained. Lock the locknut with the lock washer.
CAUTION - Excessive hydraulic pressure should not be used when setting end play, or bearing damage may occur.
NOTE: This method is directly usable on solid shaft motors, and can be utilized on some HOLLOSHAFT® motors with the use of a long threaded rod and plate. It is very easy to apply and settings can be checked quickly, especially in field service. The locknut does not see rotor weight or spring force and can be turned easily.
Special equipment required includes:
CAUTION: After setting end play by any of the above methods, run unit for fifteen minutes and recheck end play setting. If not within range, end play must be reset. All loosened or removed parts must be reassembled and tightened to original specifications. Keep all tools, chains, equipment, etc. clear of unit before energizing motor.
3. NEMA Frame Verticals with Thrust Bearing in Lower Housing
End-play setting on NEMA frame vertical motors with the thrust bearing at the lower end of the motor is accomplished by the use of shims on the outboard side of the upper guide bearing. The endplay should be determined before disassembly by using a dial indicator on the end of the shaft. After repairs are completed, the motor should be reassembled and with the original shims. The end play should be checked to insure the original setting remains. If unable to determine original endplay due to damage or other reasons, contact Product Service for values.
A: We most frequently use anti-friction / rolling element bearings. These bearings are characterized by rolling elements which separate the stationary part from the rotating part. Specific types of these bearings include:
Following is a brief description of each bearing type listed:
Deep Groove (Conrad) Ball Bearings
Typical bearing manufacturing series numbers used range from to .
Deep groove ball bearings are available in open type bearings, shielded bearings (single or double), and sealed bearings. Open type conrad bearings, which are supplied on explosion proof 180 frames and higher and ODP/TEFC 400 frames and higher, require bearing caps to contain grease in the housing. Shielded bearings, supplied on all 140 frames (ODP/TEFC through 360 frame and on all automotive duty), can be used on motors without bearing caps. Sealed bearings, which are “lubed for life”, possess a reduced speed limit due to seal friction. These sealed bearings are supplied for customer specials only.
Double Row Angular Ball Bearings
Deep groove ball bearings are the most common type of bearing for electrical motor use. These bearings are good for moderate radial and axial loads. They are used in vertical high thrust motors as a guide bearing for momentary upthrust.
Typical bearing manufacturing series numbers used range from to .
Double row angular ball bearings are very similar to single row conrad bearings, with the addition of an extra row of balls. Because of this addition, these double row bearings can handle larger radial and axial loads than conrad bearings. Double row angular ball bearings, available open, shielded, or sealed, are provided on both horizontal and vertical close-coupled pumps, and on larger normal thrust motors as thrust bearings. Sizes larger than are not readily available.
Cylindrical Roller Bearings
Typical bearing manufacturing series numbers used are preceded by an “N”. For example: N2XX or NU2XX.
Cylindrical roller bearings are used on horizontal motors where high radial loads are present. Although equivalent in size to conrad ball bearings, cylindrical bearings have a lower speed limit and are only available as open type bearings. These bearings are not available for direct connected motors, and are provided upon special order only on motors with an overhung load.
Spherical Roller Radial Bearings
Typical bearing manufacturing series numbers used range from 22,000 to 24,500.
Spherical roller radial bearings are used on horizontal motors which possess an extremely high radial load, or on motors which require an extended bearing life. Typically, these bearings are wider than conrad ball bearings, thus. making special engineering more difficult. In addition, they have a lower speed limit than cylindrical roller bearings. Spherical roller radial bearings can not withstand axial loading.
Angular Contact Ball Bearings
Typical bearing manufacturing series numbers used range from to .
Angular contact ball bearings are supplied on vertical motors only. High thrust vertical motors using single angular contact bearings are capable of continuous thrust in only one direction. Multiple angular contact ball bearings can be mounted either back-to-back for up/down thrust, or in tandem sets of two or more bearings for extra high thrust loading.
Spherical Roller Thrust Bearings
Typical bearing manufacturing series numbers used range from 29,300 to 29,400.
Spherical roller thrust bearings are supplied on vertical motors only. These bearings can support extremely high thrust loads (up to 300% of standard thrust capacity) and moderate radial loads. Preload springs are required to supply minimum downthrust to bearings at start up in order to prevent bearing skidding. In addition, the motor requires minimum downthrust at all times to compress preload springs and unload the lower guide bearing for maximum life. Water cooling is generally required.
A: For the purpose of this test, a lantern battery of six or nine volts works best. Use a DC volt-ohm meter with a 20K ohms per volt DC scale. Battery and voltmeter leads should be properly identified. Alligator clips should be used on both. The motor must be completely assembled. Test the nine leads for continuity with the ohmmeter to determine whether the motor is star (wye) or delta connected. The delta connected motor will possess three sets of three leads with continuity between them. On the other hand, the star connected motor will have only one set of three leads with continuity between them, and three sets of two leads with continuity. Following are specific steps to take when identifying leads of both a star connected and a delta connected motor.
Delta Connected Motor:
Using an ohmmeter, identify the three groups of three leads. Separate these groups by tying them with tape. Attach leads to a pair of wires in a group, and observe the voltage drop from each pair of energized leads to the third lead in that group. Continue until a combination is found that gives a voltage drop from each of the energized leads to the third lead equal to one half of the battery voltage. The lead located halfway between the other two will thus be the corner lead of the delta. Repeat this for each group of leads, marking the corner leads #1, #2, and #3.
Next, use the inductive kick test method to identify the proper markings for the other two leads of each group. The two coils #3 & #6 and 3 & #8, acting in parallel, will produce the effect of a coil positioned halfway between the actual position of the two coils. The flux produced by #3 & #6 and #3 & #8 combined, will be perpendicular to the axis of #1 & #4 and #2 & #7. Opening and closing a switch in this circuit will produce a kick in coils #1 & #9 and #2 & #5, but no kick in #1 & #4 and #2 & #7.
Therefore, if the battery is connected from #3 & #6 and #3 & #8 as shown, opening and closing the battery circuit, the voltmeter will identify leads #1, #4, and #9 and can be distinguished by noting the magnitude rather than the polarity. The voltmeter can then be connected to terminal #2 for determination of the leads #5 & #7. Leads #2 to #7 will give little or no deflection, and leads #2 to #5 will give a substantial deflection.
In succession, the battery is then transferred to the corner of #1. Tie the battery between leads #1 & #4 & #9. Making and breaking the circuit will be perpendicular to #3 & #8 and #2 & #5, resulting in no deflection. However, there will be a deflection from leads #2 & #7 and #3 & #6. Placing the battery next on the #2 & #5 and #2 & #7 leads will be perpendicular to #1 & #9 and #3 & #6 leads, therefore creating no deflection. Leads #1 & #4 and #3 & #8 would then have a deflection, thus concluding the lead testing of the nine lead delta connected motor.
Star Connected Motor:
Mark the three leads with continuity, #7, #8, and #9. Clip the battery to the #8 & #9 pair, clipping onto one and flashing the other. Clip the voltmeter to each pair of leads with continuity between them, until a pair is found that produces little to no “kick” or deflection. This pair of leads consists of the #1 & #4 leads. Next, move the battery to the #7 & #8 combination, with the positive lead on the #7 lead and the negative lead to be used for flashing the #8 lead. The voltmeter is so placed on the #1 & #4 pair that an upscale deflection is observed on the “make” of the negative #8 lead. The voltmeter positive lead is then the #1 motor lead, and the negative voltmeter is the #4 motor lead.
Next, move the battery to #7 & #9 leads with the positive lead on the #9 motor lead, and the negative to flash the #7 lead. Identification of the #3 motor lead is then determined by an upscale kick. The positive voltmeter lead should be on this lead, and the negative lead should be on the #6 motor lead. Shift the battery to the #8 & #9 pair, with the positive battery lead on the #8 lead and the negative used for the flashing. An upscale kick will identify the #2 motor lead. The positive voltmeter lead will be found on the #2 lead, and the negative voltmeter lead will be the #5 lead. This concludes the lead testing of the nine lead star connected motor.
A: Specific types of winding temperature detectors include thermostats, RTD’s, thermistors, and thermocouples. Following is a brief description of each.
Winding Thermostats
Winding thermostats are snap action, bi-metallic, temperature actuated switches. Their purpose is to activate a warning device, or simply shut down the motor upon excessive winding temperatures, when wired into the motor control circuit.
Thermostats are made either with contacts that are normally closed (open at high temperatures) or contacts that are normally open (closed at high temperatures). The thermostat temperature switch point is pre-calibrated by the manufacturer and is not adjustable. Reset is automatic after a decrease in temperature. Thermostats are normally installed in the connection end turns of the motor winding. Standard procedure is to wire three thermostats together in a set, with one thermostat embedded in each phase of the winding. Open thermostats are normally wired in parallel, while closed thermostats are wired in series. Refer to the figure below for further explanation
As seen in the figure above, only two leads come out to the motor outlet box. The leads of a normally closed (N.C. thermostat) are marked P1 and P2. Those of a normally open thermostat are marked P3 and P4.
Refer to the table below (Table 6) for thermostat alarm and shutdown temperatures.
Table 6: Thermostat Temperature Chart
Temperatures shown in ° C
RTD’s (Resistance Temperature Detectors) are precision, wire-wound resistors, with a known temperature resistance characteristic. We use flat, molded strip type RTD’s that are only .030 inch thick. RTD’s are installed in the slot portion of form wound motors, and in either the slot or end turns of mush wound motors.
RTD’s used in motor windings are either 10 ohm, 100 ohm, or 120 ohm. Each type of RTD has its own specific resistance characteristic. The basic detectors are listed below in Table 7.
Table 7: Winding RTD’s
* Also available with 3 leads.
All the RTD leads are brought out to a motor outlet box. RTD’s leads are identified in sets, using C1, T1, T1, and C11, T11, T11 for the same phase. Since leads are always brought to terminal strips, the leads are terminated with fork-tongue terminals.
See alarm and trip temperatures based on the motor service factor, HP rating, and class of temperature rise.
Winding Thermistors
A thermistor is a non-linear resistance temperature detector, made from semi-conducting material. We utilize positive temperature coefficient (PTC) type thermistors, which have a resistance that increases with increasing temperature. Each individual thermistor has its own unique resistance vs. temperature characteristic. Thermistors are normally installed in the end turns of the motor. Depending upon the controller, they are wired either in series or in a ‘common lead circuit’. Both circuits are shown below.
The following is a brief description of the controllers and thermistors supplied by various companies:
Power Control Corporation (PCC)
In the past, we supplied PCC 600, 900, , and series thermistors. We now use only the series thermistors. A maximum of three PCC series thermistors are installed in the common lead circuit configuration. Do not install them in series, or false tripping will result. PCC makes numerous controllers, including a special controller for the therma-sentry system. The PCC controller brand name is ‘MOTOGUARD’. For non-therma-sentry PCC thermistors, the thermistors are internally wired in the common lead configurations with the leads marked TM5, TM6, TM7, and TM8. Lead TM5 is the common lead.
Texas Instrument (TI)
TI currently uses 4BA and 7BA series, PTC thermistors. The 4BA series thermistors are normally used on new and rewound motors and contain a copper heat collector for a fast response time. The 7BA series is normally used on existing motors, and contains only a small thermistor bead to ease installation. TI thermistors are wired in series. Three thermistors may be installed in series without false tripping the controller. Our procedure is to bring out all six leads and make the series connection in the outlet box. The thermistor lead pairs are marked TM1, TM2, and TM3. The standard TI controller is a 50AA control module.
Siemens
We presently use a Siemens Q-P, PTC thermistor. Siemens thermistors must be wired in series. Six thermistors may be wired in series without false tripping the controller. Our standard procedure is to install three thermistors in series and bring all six leads out, making the series connection in the outlet box. The thermistor lead pairs are marked TM1, TM2, and TM3. The Siemens standard controller is a 3UN tripping unit control module, which has an N.O. and an N.C. contact.
The following table (Table 8) shows alarm and shutdown temperatures (in ° C) for 1.0 and 1.15 SF thermistors, based on the required class of temperature rise.
The new Thermasentry® system utilizes Siemens BM thermistors connected in series and a Siemens 3RN controller.
Table 8: Thermistor Temperature Setting Chart
Temperatures shown in ° C
Service Factor
1.0
1.15 - UP
Purpose
ALARM
SHUTDOWN
ALARM
SHUTDOWN
Class of Temp. Rise
A
B
F
A
B
F
A
B
F
A
B
F
Open Motors w/o Ducts
PCC, PTC
105
If you are looking for more details, kindly visit cast iron Electric Motor Housing.
115
145
115
125
155
105
125
155
115
135
165
TI, 4BA Series
105
115
145
115
125
155
105
125
155
115
135
165
TI, 7BA Series
105
115
145
115
125
155
105
125
155
115
135
165
Siemens
100
120
140
110
130
155
110
130
155
120
140
160
Open w/Ducts and TEFC Motors
PCC, PTC
105
125
155
115
135
165
115
135
155
125
145
165
TI, 4BA Series
105
125
155
115
135
165
115
135
155
125
145
165
TI, 7BA Series
105
125
155
115
135
165
115
135
155
125
145
165
Siemens
110
130
150
120
140
160
120
140
155
130
150
160
Thermocouples
A thermocouple is a pair of dissimilar conductors joined at one point, in a way that causes an electromotive force (EMF) to develop due to the thermoelectric effects. Any given set of thermocouple wires has a known EMF vs. temperature characteristic. Thermocouples are only able to generate a low-voltage, low-power signal in the millivolt range. There are many types of thermocouples. Standard types include copper-constantan, chromel-constantan, and iron-constantan. Thermocouples are normally installed in the slot between coil sides, on both mush wound and form wound motors. However, if necessary, they can also be installed in the end turns. The standard quantity of thermocouples is six, installed two per phase. If quantity-3 thermocouples are specified, leads are marked TC1, TC2, and TC3. If quantity-6 are specified, leads are marked TC1, TC2, TC3, and TC11, TC22, TC33, such that TC1 and TC11, etc. are in the same phase.
See alarm settings for alarm and trip temperatures based on the motor service factor, HP rating, and class of temperature rise.
If you want to learn more, please visit our website OEM valve casting parts.