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.
Flow Rate
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.
Measurement Data
September 2021
Measurements made on a Fluke 322 meter.
| L1 to GND | 117 VAC |
|---|---|
| L2 to GND | 211 VAC |
| L3 to GND | 120 VAC |
| L1 to L2 | 240 VAC |
|---|---|
| L2 to L3 | 240 VAC |
| L3 to L1 | 238 VAC |
| 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.
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 (VFD)
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.
Safety
A safety relay (reset and E-stop circuits) and additional contactor (maybe two contactors w/o STO) are likely required.
A load reactor likely will not be used, nor does it necessarily eliminate the need for shielded VFD cabling.
Bill of Materials
| Quantity | Description | Cost Each | Total Cost | Comment |
|---|---|---|---|---|
| 1 | DURApulse GS23-2015 | $614 | $614 | Presently out of stock. |
| 1 | LR-2020 59.4 A 3 % Series Line Reactor | $195 | $195 | |
| 2 | Hoffman Polycarbonate Enclosures (TBD) | TBD | TBD | TBD |
| 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) | $75 | $75 | Estimated eBay cost. |
| 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 |
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)
Past Considerations
Power Factor Correction Capacitor (PFCC)
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.