Pool Main Pump Motor

The pool main pump motor identification plate.

The main pool pump motor at the facility (as of August 2021) is a Leeson Model C254T17DK13A (catalog #199987.00). It is rated for 15 HP (11 kW), 37 FLA @ 230 VAC. It is inverter duty rated (confirmed by the local manufacturer's rep) with a 10:1 PWM ratio (60 Hz, 1770 RPM down to 6 Hz, 177 RPM).

It has a month/year manufacturing designation of "H2016" - presumably corresponding with August (H=8) 2016. This makes sense, as the pump was noted to have been replaced in early 2017.

Operation

Starting and Stopping

This is performed via the motor starter. Further details on hold, pending replacement with a VFD.

Flow Adjustment

The pump flow is adjusted via the butterfly valve on the output side of the pump. The flow rate must be periodically adjusted via this valve as debris in the strainer basket and sand filters provides additional resistance.

In the future, a VFD may be used to reduce the motor speed, eliminating the need for manual adjustment via a valve.

Maintenance

Lubrication

Use Mobil Polyrex EM (or equivalent Polyurea grease for electric motors), 3-4 pumps per port (i.e. front and rear of the motor). Lubrication should be performed twice per season.

Wiring and Fuse Protection

The motor is supplied 3-phase "high-leg delta" 240 VAC. This is an asymmetrical supply (relative to earth ground); see measurements in the appendix. There are two disconnects: one in the basement of the club house (fused at 100 A) and one in the pump house (fused at 60 A). See the Electrical System diagram for details.

The existing motor is fed by 3 x TBD (#10 AWG GND). Fused with 3 x FRN-R-60 (60 A) fuses.

Thermal Monitoring

At this time, no thermal monitoring is performed on the motor. It does not appear the motor has any embedded temperature sensors. The possibility of adding thermocouples is being investigated.

Variable Frequency Drive

IMPORTANT: At this time, this section is for investigation purposes only. It has not been determined when/if a VFD will be implemented.

Justification

As of Fall 2021, the pump is controlled by a Square D 8536 latching motor starter (relay). The pump is manually operated via start and stop pushbuttons. The flow rate is adjusted via the butterfly valve on the output side of the pump.

Removal of the motor starter and replacement with a VFD has been proposed. This system would be implemented prior to the 2022 swim season.

Benefits to changing to the VFD include:

• Motor speed can be automatically adjusted (via the automation system) to compensate for changes in flow rate due to the state of the strainer basket and sand filters. A constant and flow rate can be assured until the strainer basket or filters become too clogged. The automation system is NOT required to operate the drive. In the event that the automation system is not operational (or remote VFD control is disabled), the VFD can be operated with start and stop pushbuttons in a manner very similar to that of the motor starter.
• No need for the operator (managers or B&G personnel) to regularly adjust the flow rate due to changing conditions. An improper flow rate:
  • Violates best practices and/or health department requirements if too low (minimum number of complete water turn-over cycles per 24 hour period).
  • Causes channeling in the sand filters due if too high. This can lead to incomplete filtration (cloudy water) and requires opening and manually stirring tank sand to resolve.
• Utility incentives will pay for a significant portion of the material cost. As of 2022, DTE will reimburse up to $900 for a 15 HP VFD.
• Enhanced safety with the addition of two emergency stop buttons, including one at the gallery level (near the pump).
• Reduced stress on the mechanical system during startup as the motor speed can be ramped up rather than instant-on. This prevents "hammering" that can occur from an abrupt start.
• Improved fault detection. The drive can detect shorts, over-current events, low voltage, phase loss, etc. The existing configuration relies solely upon fuses, which may not offer the same level of protection.
• Improved power factor. An improved power factor reduces losses in the cabling between the distribution panel in the clubhouse basement and the pump house.

There are some downsides, too:

• Material cost (see the bill of materials).
• Added complexity.
• Added failure points - including the addition of sensitive electronics in a harsh environment.

An improvement in energy efficiency may be possible. However, it is not confirmed. Restricting the output flow on a centrifugal pump reduces the amount of work (pushing a lower volume weight of water). Data in the appendix below confirms this to a point.

Requirements

• Must withstand an ambient operating range in the 40 °C to 50 °C (122 °F) range. For the GS23-2015 at 75% load, 50 °C, no de-rating is necessary up to a 4 kHz carrier frequency (SVPWM mode).
• Must be compatible with 240 VAC high-leg delta.
• A two-channel safety relay will be used.

Theory of Operation

The sections below are theoretical at this point, describing possible operation for the VFD controls.

Reset

The state of "reset" refers to the operating state of the safety relay. In order to operate the VFD, the safety relay must be reset by pressing the reset pushbutton. The safety relay cannot be reset if an Emergency Stop switch is tripped.

Power failure will cause a loss of reset. Unfortunately, this is required for safety, as an electromechanical interlock ensures the motor will not start automatically (without explicit operator intervention). Even with a safety module, the electrical disconnect should still be used when maintaining the motor or pump.

Run

Pressing the Run pushbutton causes the VFD digital input (FWD/DI1) to go HIGH (+24V). Assuming the safety module is reset, the VFD will ramp up to full speed (60 Hz). The speed may be reduced via closed-loop control from the automation system (based upon flow meter feedback). By defaulting to 60 Hz, the motor can be operated normally without the automation system, using the butterfly valve on the output side of the pump to adjust flow.

A VFD digital output (DO1) illuminates the green LED embedded in the Run pushbutton.

Stop

Pressing the Stop pushbutton causes the VFD digital input (DI3) to go LOW (no longer connected to +24V). The VFD will ramp down to zero speed.

A switch guard (cover) may be placed on the stop button to deter its use (in favor of Programmed Stop). In an emergency, the Emergency Stop pushbutton can still be easily accessed.

Programmed Stop

Pressing the Programmed Stop pushbutton notifies the PLC (automation system) that a pump stop is requested. The pump may not stop immediately; this pushbutton is not connected to the VFD. Instead, if the boiler is operating, it is disabled and allowed to cool. Once the boiler has cooled sufficiently, the pump is stopped.

An indicator in the Programmed Stop pushbutton blinks periodically during the period between when the button is pushed and the pump motor is stopped. Pressing the button repeatedly has no effect; the programmed stop cannot be canceled. When desired, the user may press the Run pushbutton to resume pump motor operation.

The term "Programmed Stop" may be changed to something better or more descriptive.

NOTE: Existing blue control wires 20080, 20090, 21071 and 22131 could be re-used for this pushbutton. At present, these wires are used to force-stop the motor starter and provide feedback. Refer to FFSC-001 Pg 41 - Pump House Motor.png.

VFD Unit

Overview

Cost is a major driver in the VFD selection process. As noted, up to $900 will be reimbursed by DTE. Longevity is an issue, too, as failure becomes a MAJOR issue for pool operation.

The consensus amongst "experts" (i.e. individuals with opinions in forums) is that:

• ABB or Allen Bradley drives are top-of-the-line, but come at a cost. ABB drives are very easy to program (but expensive!).
• Automation Direct drives are inexpensive - but support is lacking. Later-generation drives (such as the GS23, made by Delta) seem to receive positive feedback. Earlier generations (GS1, GS2) are to be avoided. Much of the negative feedback seems to be 10+ years old.
• Delta is usually regarded as "decent" (again, Automation Direct GS23 line).
• Teco may be a step up from Automation Direct and Delta?
• Vacon is well-regarded.
• Yaskawa is recommended both in online forums, and by engineers at a local industrial controls firm.

Yaskawa GA50U2042ABA

The present front-runner.

• Priced at $842 via local distribution.
• The 2042 model sized for "normal duty" (ND) 15 HP which is appropriate for variable torque (VT) applications (i.e. centrifugal pumps).
• Internal PCBs are conformally coated (IEC 60721-3-3, Class 3C2 for chemical gasses). This is a huge plus!
• Rated for -10 °C to +50 °C (122 °F).
• 42 A current rating. Exceeds the FLA of the motor (37 A) with a 14% margin.
• No built-in DC link reactor (can be added externally between terminals +1 and +2).
• No built-in EMC filter (desirable for non-symmetric 3-phase supply).
• Frame 5 is 10.24" H x 5.51" W x 5.51" D
• Required vertical-installation clearance is 3.94" top/bottom, 1.18" sides.
• 391 W total loss @ 2 kHz, 42 A output.

Automation Direct GS23-2015

The alternative (and past front-runner).

Automation Direct GS4-2015

Not presently being considered.

• Substantially larger: 12.60" L x 7.48" W x 7.48" D (versus 8.15" L x 4.29" W x 6.06" D for the GS3).
• Support for 1-phase operation (not needed for this application).
• Slightly reduced CT/VT ratings: 47A/49A vs. 49A/51A for the GS23.
• Slightly worse low temperature rating: -10 °C vs. -20 °C for the GS23 (not an issue).
• No FOC or torque control mode?
• No USB port?
• Slightly more/better analog/digital I/O options vs. the GS23 (not needed for this application).
• Might not be compatible with permanent magnet AC motors?

ABB ACS310-03U-50A8-2+J400

Not presently being considered.

Line Reactor

Automation Direct recommends an LR-2015 (46.2 A, 0.22 mH, 3-phase, 4.25" H x 7.2" W x 4.75" D) for $179 on Automation Direct.

A 3% impedance reactor absorbs transients and prevents nuisance tripping of drives in most applications. A 3% impedance line reactor is typical for the line side. A 5% impedance reactor can be used if the harmonic content is severe or if IEEE519 recommendations should be met. The reactor impedance magnitude is said to be equal to the voltage drop.

Multiple alternatives to the LR-2015 have been evaluated:

• MTE RL-04501 (45 A, 0.300 mH, 3-phase, 4.60" H x 8.91" W x 7.13" D) for $289.31 on Galco or far less on eBay. This is a very large part.
• MTE RLW-004601 (42 A, 3.68" H x 6.00" W x 5.76" D). Not readily available.
• TCI KDRD24L (208/240 VAC 48 A 15 HP, 3-phase, 3% - Low Z, 3.82" H x 6.95" W x 5.57" D). $195.94 on Galco (eBay TBD).
• Hammond CRX0046AC (46 A, 0.21 mH, 15 HP, 3-phase, 3%, 5.00" L x 6.13" H x 4.38" D, 40 Watts). Not readily available on eBay.

To evaluate further:

• Baldor LRAC04501 (45 A, 0.3 mH).
• For the Yaskawa GA50...2042 Normal Duty (ND) 15 HP, an Yaskawa open frame 3% URX000323 (35 A, 0.35 mH) or 5 % URX00324 (35 A, 0.71 mH) reactor is recommended.

Drawings

The Line Reactor Placement Study sheet has been created to help evaluate the physical fit of multiple line reactors. To keep the cost low, multiple options are being considered.

Additionally, concurrent designs for the GS23-2015 and GA50U2042ABA are in development.

Bill of Materials

The list below is updated as of 5-Jan-2022. Some items have been pre-emptively purchased (anticipating board approval; can be re-sold otherwise).

The list below does not include parts for "Programmed Stop", nor does it include cooling fans and filters. The VFD motor cable (if used) is also not included.

Quantity	Description	Cost Each	Total Cost	Comment
1	DURApulse GS23-2015	$614	$614	In stock as of January 2022.
1	Line Reactor (see section below)	$50	$50	eBay estimate (deal pending).
2	Hoffman Q403018PCICC Enclosure	$150	$300	Based on $206.25/ea @ Zoro w/ 20% discount.
2	Hoffman Q4030PI Panel	$26	$52	Searching eBay, etc.
2	Hoffman Q4030EXTI Extension Ring	$42.40	$84.80	Purchased on eBay 8-Dec-2021.
3	Edison TJN110 110 A Class T Fuse	$28	$83	110 A for the GS-2015; 150 A for the GA50U2042ABA.
1	Marathon T200A3B Class T Fuse Block Holder	$50	$50	Estimated eBay cost. To confirm fit with TJN110.
1	Pilz PNOZ X3 Safety Module 774316 (120 VAC)	$37.10	$37.10	Purchased on eBay 6-Dec-2021.
1	Marathon 1423570 Power Dist Block	$25	$25	Estimated eBay cost.
1	White LED Pushbutton GCX3206-24L w/ "Reset" Plate	$24	$24
1	Green LED Pushbutton GCX3202-24L w/ "Run" Plate	$23	$23
1	Red Pushbutton GCX3101 w/ "Stop" Plate	$9	$9
2	E-Stop Pushbutton GCX3136 w/ Ring & Extra Contact	$19	$38

Total: $1494 (estimated)

Not Included: DIN rail, terminals, small fuse terminal(s), control wire, etc.

Motor Cable

Shielded VFD cabling may be required to contain high-frequency emissions. Automation Direct has #8 AWG 4-conductor XLPE insulated shielded cable, rated for 50 A at 75 °C (NEC 310.15 (B), assumes 30 °C ambient) for $8.08/ft (August 2021 pricing). The cable is made in USA by Southwire. This cable has an OD of 0.87 inches and minimum bend radius of 10 inches. Calculations suggest a 1-1/4" conduit may be necessary to pull a cable of this diameter with adequate fill margin. The existing PVC conduit appears to be about 3/4" (to confirm), which would need to be replaced.

Bypass

A bypass mechanism can be used to operate a motor in the event of VFD failure. No wired bypass will be implemented due to cost/space. However, the component/wire layout will be such that bypass should be possible with minimal effort.

Prior Modifications Evaluated

Power Factor Correction Capacitor

At present (as of August 2021), no power factor correction capacitor (PFCC) is in use. It was decided that given cost priorities, a PFCC would not offer sufficient payback to justify its purchase.

Myron Zucker was contacted in August 2020 and provided two options, both rated for 240 VAC, 5 kVAr, 3-phase, 60 Hz:

• KNM23005-3 (NEMA 12 for indoor use, 14" H x 9.25" W x 5.25" D)
• KNM23005-3N3 (NEMA 3R suitable for outdoor use, 16" H x 12" W x 6" D)

Applying a 5 kVAr PFCC would reduce the FLA from 37 A to 31 A. This would reduce i-squared-R losses by 6 A. Actual losses are then based upon the cable run.

Appendix

Measurement Data

Measurements made on a Fluke 322 meter in September 2021.

Line to Ground Voltage:

L1 to GND	117 VAC
L2 to GND	211 VAC
L3 to GND	120 VAC

Line to Line Voltage:

L1 to L2	240 VAC
L2 to L3	240 VAC
L3 to L1	238 VAC

Current Consumption:

	Trial #1	Trial #2	Trial #3	Trial #4
L1	34.3 A	35.2 A	27.8 A	32.5 A
L2	35.5 A	36.0 A	29.2 A	33.6 A
L3	32.2 A	33.2 A	26.2 A	30.4 A
Tank Pressures	9-10 psi	11-12 psi	0-1 psi	5-6 psi
Flow Rate	617 GPM	694 GPM	248 GPM	476 GPM
Total Power (See Note 1)	14.133 kVA	14.466 kVA	11.529 kVA	13.371 kVA

• Trial #1: The output flow valve is cut back to just shy of 45° (half closed). The input flow valve is fully open.
• Trial #2: The output and input flow valves are fully open.
• Trial #3: The output flow valve is cut back far (very restricted). The input flow valve is fully open.
• Trial #4: The output flow valve is fully open. The input flow valve is very restricted.

Notes:

• Note 1: The total power calculation is based on the average current of all three phases, multiplied by 240 V, multiplied by the square root of 3.
• The power factor (PF) according to the motor plate is 0.81, but it's not known how this applies to the particular loads in each trial.