Pool Main Pump Motor
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 outflow 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 existing motor is fed by 3 x TBD (#10 AWG GND). Fused with 3 x FRN-R-60 (60 A) fuses.
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.
An Automatic Direct DURApulse GS23-2015 VFD has been chosen over multiple competing options. The feature set and pricing is very competitive.
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.
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.
Emergency Stop
Bill of Materials
The list below is updated as of 1-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".
| Quantity | Description | Cost Each | Total Cost | Comment |
|---|---|---|---|---|
| 1 | DURApulse GS23-2015 | $614 | $614 | In stock as of January 2022. |
| 1 | LR-2020 59.4 A 3 % Series Line Reactor | $195 | $195 | |
| 2 | Hoffman Q403018PCICC Enclosure | $153 | $206 | Looking for lower-cost options. |
| 2 | Hoffman Q4030PI Panel | $26 | $52 | |
| 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 | |
| 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.
Configuration
- Use Variable Torque (VT) mode for pump control (power is proportional to the cube of the speed)
Alternatives Evaluated
Automation Direct GS4-2015
- 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 GS3.
- Slightly worse low temperature rating: -10 °C vs. -20 °C for the GS3 (not an issue).
- No FOC or torque control mode?
- No USB port?
- Slightly more/better analog/digital I/O options vs. the GS3 (not needed for this application).
- Might not be compatible with permanent magnet AC motors?
Others
- ABB ACS310-03U-50A8-2: Larger, expensive ($1,100).
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.