General Construction Specifications
PART 1 - GENERAL
01 DESCRIPTION OF WORK
A. Under this item the Contractor shall furnish, install, test and place in operation a complete and operational Variable Frequency Pump Drive System (VFDS).
B. The VFDS shall be supplied by the pump manufacturer as specified. The pump manufacturer is responsible for any interfacing required to provide a complete operational system.
C. Any exceptions or deviations shall be defined in writing at the time of Bid.
D. The VFDS shall be designed for varying the flow rate of the raw sewage pumps in the pump station. The complete drive system, although described as separate items, shall meet the overall design requirements as specified herein.
02 SUBMITTALS
A. The Engineer reserves the right to approve or disapprove any and all based upon evaluation. Approval for fabrication and installation will be made only after submittal and review of all shop drawings. The information required for approval shall include the following information and shall be submitted with the pump controls submittals.
1. 3-line electrical diagram of the power and control system.
2. Complete electrical schematics detailing every wire and connection within the system as well as all field connections.
3. Bill of material and product data sheets on all high voltage components (>120VAC), drives, switches, and other critically important components.
4. Equipment dimensions, including stub-up locations, shipping splits and shipping weights.
5. Catalog cuts of major components.
6. Spare parts lit.
7. Certifications, including:
a) Warranty
b) Efficiencies
B. All submittals shall be in accordance with Section 01340.
C. Harmonic Voltage Distortion Analysis:
1. With the shop drawings, the manufacturer of the variable speed pump control shall submit to the Engineer a detailed harmonic voltage distortion analysis which shall include at least the following:
a) Calculation of percent voltage distortion, with respect to the fundamental voltage, on the line side bus.
b) Comparison of calculations with IEEE-519 Standards for acceptable voltage distortions on such systems.
2. This analysis shall be based upon the minimum three phase bolted fault short circuit current available at the point of electrical service.
D. All furnished under this section shall be warranted by the Contractor and the manufacturers for a period of one (1) year after completion of startup.
E. All shall be warranted to be free from defects in workmanship and materials. The variable frequency drive converter and inverter SCR's shall be warranted for a period of five (5) years after shipment. Any inverter or converter SCR which fails during this period shall be replaced by the VFD manufacturer.
PART 2 - PRODUCTS
03 ACCEPTABLE MANUFACTURERS
A. Robicon Corporation, Pittsburgh, Pennsylvania
B. Allen-Bradley
C. General Electric
04 GENERAL
A. The variable frequency drive (VFD) motor controller shall convert 2.3K volt, three-phase, 60 Hz utility power to adjustable voltage (0-2.3) three phase, AC power for stepless motor speed control with a 4:1 speed range. The VFD must be capable of sustained operation at 1/4 speed to facilitate checkout and maintenance of the driven equipment.
All general options and modifications shall mount within the standard adjustable frequency controller enclosure.
B. The VFD motor controller shall be suitable for use with the motors supplied by the pump manufacturer. The VFD manufacturer shall coordinate with the pump manufacturer to provide a operational system.
C. The adjustable frequency controller shall be a current source, six-step design as manufactured by Robicon Corporation or PWM-CSI design as manufactured by Allen-Bradley or approved equal. All drives shall be supplied by one manufacturer.
D. The variable frequency controllers shall operate satisfactorily when connected to a bus supplying other solid state power conversion or when other VFD's are operated from the same bus. The VFD's shall not create voltage distortions greater than the acceptable standard per IEEE-519 for system as designed.
E. The variable frequency controllers shall include transient voltage suppression to allow reliable operation on a typical commercial power distribution system.
F. The drives shall not utilize any double transformation.
2.03 SCHEDULE
A. Drives shall be of the quantity as shown on the Contract Drawings. Drives shall be of the size and capacity to operate the wastewater pumps without overloading the drives.
2.04 BASIC DESCRIPTION
A. The controller shall produce an adjustable AC voltage/frequency output. It shall have an output voltage regulator to maintain correct output V/Hz despite incoming voltage variations.
B. The controller shall have a continuous output current rating of 100% of motor nameplate current.
The variable frequency drive(s) shall be air cooled, current source design. Water cooled designs are not acceptable. The VFD shall consist of converter, link inductor and inverter sections. All SCR's in the converter and inverter shall be standard rectifier grade devices of sufficient capacity so that redundant or "backup" devices are not required. The SCR's shall carry the SCR manufacturer's standard part number such that they can be readily cross-referenced and interchanged with other SCR manufacturer's devices. SCR's which are matched or color-coded for specific turn-off characteristics are not allowed.
C. The converter section shall be a full wave, phase controlled, 3-phase converter to change the input AC power to DC power. The converter bridge legs shall utilize single SCR's or GTO's in conjunction with a PWM switching pattern to produce near sinusoidal output waveforms only, for minimal parts count and highest reliability. Multiple "stacked" SCR's are not allowed. Supply sample output current and voltage waveforms at 20, 30, 45 and 60 Hz.
D. The output of the converter shall feed an inductor and the converter/inductor combination shall form a current source whose output is regulated and limited. The current limit feature of the converter shall be sufficiently fast and effective so as to protect against a sudden and/or random application of a short circuit to the output terminals of the current source.
E. The inverter section shall convert the DC power of the current source to adjustable frequency power to the motor. The VFD shall not induce excessive power losses in the motor. The worst case RMS motor line current measured at rated speed, torque and voltage shall not exceed 1.05 times the rated RMS motor current for pure sine wave operation.
F. The drive shall contain an input AC reactor to allow the VFD to operate properly without an isolation transformer. The reactor shall attenuate the commutation notches generated by the VFD. The line reactor shall be mounted and wired within the drive enclosure.
G. The control logic section shall be fully digital and not require the use of plug-in circuit cards. Analog adjustment pots are not allowed. The microprocessor shall be a 16-bit address, 8-bit data device, with 256 bytes of internal RAM.
8K-bytes of supplementary on-board static RAM shall be furnished. The program memory shall be stored in a 32K-byte electrically programmable ROM. Data and parameter storage shall be in non-volatile memory.
2.05 BASIC FEATURES
A. The VFD controller shall have the following basic features:
1. The door of each power unit shall include a "POWER ON" light, a VFD fault light, a VFD run light, stop pushbutton, start pushbutton, a fault reset pushbutton, a "HAND-OFF-AUTOMATIC" selector switch, and a manual speed control potentiometer.
2. The VFD shall be selectable to provide automatic restart after a trip condition resulting from overcurrent, overvoltage, undervoltage, phase failure, or overtemperature. For safety, the drive shall shut down and require manual reset and restart if the automatic reset/restart function is not successful within a maximum of three attempts within a 10 minute time period.
3. A speed drop feature shall be included which reduces the speed of the drive on transient overloads. The drive is to return to set speed after transient is removed. If the acceleration or deceleration rates are too rapid for the moment of inertia of the load, the drive is to automatically compensate to prevent drive trip.
4. Automatic restart after drive trip or utility failure. Software selectable if not desired.
5. Speed profile. Individual adjustable settings for start, stop, entry, slope, and minimum and maximum speed points.
6. Process signal inverter. Software selectable to allow speed of drive to vary inversely with input signal.
7. Proportional and integral process controller with menu driven selection and programming via door-mounted keypad and/or remote ASCII terminal.
8. Pick up a spinning load. The VFD shall be able to determine the motor speed and resume control of a motor which is spinning in either direction without tripping.
9. A door-mounted digital keypad/display unit shall be provided and capable of controlling the VFD and setting drive parameters.
10. The digital display shall normally display:
a) Speed demand in percent.
b) Output current in amperes.
c) Frequency in hertz.
d) Control Mode: Manual/Automatic
e) Total three-phase KW (actual measured KW)
11. The keypad will display diagnostic messages and parameter values when accessed.
12. The digital keypad shall allow operators to enter exact numerical settings in English engineering units. A user menu is to be provided as a guide to parameter setting. Coded messages on the keypad will not be acceptable. Drive parameters are to be factory set in EEPROM and resettable in the field through the keypad. Three (3) levels of password security shall be available to protect drive parameters from unauthorized personnel. The EEPROM stored drive variables must be able to be transferred to new boards to reprogram spare boards.
13. The keypad/display shall have a key switch to control operation of the keypad. Key to be removable in either "ENABLED" or "DISABLED" positions. Keypad module shall contain a "self-test" software program that can be activated to verify proper keypad operations.
14. The VFD shall not require an output contactor to protect the power circuit components from damage due to the following fault conditions:
a) Single-phase fault or three-phase short circuit on VFD output terminals.
b) Failure to commutate inverter SCR due to sever overload or other conditions.
c) Loss of input power due to opening of VFD input disconnect device or utility power failure during VFD operation.
d) Loss of one (1) phase of input power.
e) Motor regeneration due to backspin or loss of VFD input power.
15. The VFD shall be able to withstand the following fault conditions without damage to the power circuit components:
a) Failure to connect a motor to the VFD output.
b) VFD output open circuit that may occur during operation.
16. Each VFD shall have a built in V.P.S. system for control power.
2.06 SERVICE CONDITIONS
A. The controller shall be designed and constructed to operate within the following service conditions:
1. Elevation: To 3300 feet
2. Ambient Temperature Range: 00C to 400C
3. Atmosphere: Non-condensing relative humidity to 95%
4. AC Line Voltage Variation: -5% to +10%
5. AC Line Frequency Variation: +3 Hertz
6. Guaranteed minimum VFD efficiency shall be 97% at 100% speed and 100% torque and 88% at 50% speed based on nominal 1800 RPM motor with load horsepower to vary as cube of speed.
2.07 ENCLOSURE
A. All VFD system components shall be mounted and wired by the VFD manufacturer in a dead-front grounded enclosure meeting the following requirements.
1. NEMA-1 design, of sufficient rigidity to prevent door or panel "oil- canning".
2. Suitable for back-to-back installation or against a wall. Rear cabinet access is not allowed.
3. Arranged for bottom conduit entry/exit.
4. Painting and finish to be in accordance with Spec Section __________.
5. Suitable for mounting on a 4" concrete housekeeping pad.
2.08 PROTECTIVE FEATURES AND CIRCUITS
A. The controller shall include the following protective features:
1. Static instantaneous overcurrent and overvoltage trip.
2. Phase sequence detector and undervoltage protection.
3. Power unit overtemperature protection.
4. Electronic motor inverse time overload protection.
5. Responsive action to motor winding temperature detectors or thermostatic switches. A dry contact (NC) input to the VFD will be required.
6. The VFD shall be capable of transient operation with a line voltage dip of 15% of normal operating voltage on a variable torque load. During line dip, the VFD shall automatically provide a speed droop limiting maximum capable speed for the duration of the input voltage dip.
7. When power is restored after a complete power outage, the VFD shall be capable of catching the motor while it is still spinning and restoring it to proper operating speed.
8. The power circuit design shall be such that the following fault conditions can occur without damage to the power circuit components:
a) Single phase fault or three phase short circuit on VFD output terminals.
b) Failure to commutate inverter SCR or GTO due to severe overload or other conditions.
2.09 ADJUSTMENTS
A. The controller shall have the following adjustments accessible through a keypad display unit and/or remote ASCII terminal.
1. Parameter Settings:
a) Motor Nameplate Data:
1) Motor frequency
2) Number of poles
3) Full load speed
4) Motor volts
5) Motor full load amps
6) Motor KW
7) Current limit, minimum
8) Current limit, maximum
b) VFD limits:
1) Independent accel/decel rates
2) Motor flux buildup delay: time/amount
3) Vmin, Vmax, V/Hz and motor slip
4) 1 boost
5) Overload trip curve select (Inverse or Constant)
6) Min/Max speed (frequency)
7) Auto reset for load or voltage trip select
8) Slip compensation
9) Catch-a-Spinning-Load select
10) Overload trip time set
c) VFD Parameters:
1) Voltage loop grain
2) Voltage loop stability
3) Current loop stability
d) Controller Adjustments:
1) PID control enable/disable
2) Setpoint select
3) Proportional band select
4) Reset time select
5) Rate time select
6) Input signal scaling
7) Input signal select 4-20mA/0-5 Volts)
8) Auto stat functions: On/Off, Delay On/Off, Level Select On/Off
9) Speed Profile: Entry, Exit, Point Select
10) Min., Max. Speed Select
11) Inverse profile select (allows VFD speed to vary directly or inversely with input signal.)
B. All drive setting adjustments and operation parameters shall be stored in a parameter log which lists allowable maximum and minimum points as well as the current set values. This parameter log shall be accessible via an RS232 serial port as well as on the keypad display and/or remote ASCII terminal.
04 DIAGNOSTIC FEATURES AND FAULT HANDLING
A. The following conditions shall cause a safe drive shutdown:
1. Loss of input power
2. Undervoltage
3. Sustained gradual overload
4. Instantaneous severe overload
5. Power SCR/GTO overtemperature
6. Blown fuse
7. Logic power supply failure
B. The VFD shall include a comprehensive microprocessor based digital diagnostic system which monitors its own control functions and displays faults and operating conditions. Microprocessor systems must be products of the same manufacturer as the VFD (to assure single source responsibility, availability of service and access to spare parts). The diagnostic display must be a 4 line, 20 character LCD display.
C. A "FAULT LOG" or fault trace feature shall record, store, display and print upon demand, the following for the 50 most recent events.
D. A "HISTORIC LOG" or tread buffer feature shall record, store, display and print upon demand, the control variables.
1. Type of fault:
a) Br over current
b) Br under voltage
c) Br phase rotation
d) BR fuse failure
e) Sustained overload
f) Manual trip test
g) Power supply fail
h) Output over voltage
i) Inverter over temperature
j) Thermistor trip
k) Ground fault
l) Main logic
m) Rectifier/inverter logic
n) Line contactor
o) Logic power
p) DC link O.V.
q) Inverter gating
r) UPS failure
s) D.C. line o.c.
t) Rectifier/inverter devices
2. Drive inhibit (On/Off)
E. The fault log record shall be accessible via a RS232 serial link and/or ASCII terminal as well as line by line on the keypad display.
05 DRIVE OPTIONS
A. Provide the following options/modifications to the VFD. All special features shall be factory mounted and wired within the VFD enclosure unless otherwise specified.
1. Input fused isolating switch, interlocked with the enclosure door, with through-the-door handle to provide positive disconnect of incoming AC power.
2. Door-mounted meters as follows:
a) Analog ammeter (0% - 110%).
b) Analog speed/frequency meter (0 - 110% speed as well as Hz).
c) Analog voltmeter (0 - 600 VAC).
d) Analog KW METER (0 - 110%).
e) 5-digit elapsed time meter.
2. The VFD's shall be provided with contacts for operation of the motor heaters and solenoid valves for the seal water to the pumps. The power supply for the motor heaters shall be supplied from the VFD.
3. The drive is to be provided with isolated 4-20mA DC output signals proportional to speed, current, voltage and/or KW for connection by others as required.
4. Provide a door-mounted RS232 port for the connection of an printer.
5. A portable battery powered thermal printer with RS-232C serial interface and connecting cable shall be furnished. The printer shall have a dot matrix format with a print speed of 37 CPS and a 1500 line print capability per battery charge. Operating life shall be at least 500,000 lines.
6. The VFD's shall provide for power factor correction to 95%.
2.12 SYSTEM OPERATION
A. The speed of the drives shall be controlled by the pump control system as specified in Section 11100 - Instrumentation. The VFD manufacturer shall coordinate with pump control system manufacturer to assure a complete operational system.
B. The VFD system shall consist of three AC drives connected to the pump control system. The pump control system will monitor the levels in the wet well and shall run the VFD drives as required to maintain the levels in the wet well. Provisions shall be made for a future VFD unit.
C. Each drive shall be capable of serving as a lead, lag or lag-lag controller. The pump control system shall control the sequence timing of each of the three drives based on signals from the digital outputs.
2.13 QUALITY ASSURANCE AND FACTORY TESTS
A. The controller shall be subject to, but not limited to, the following quality assurance controls, procedures and tests:
1. The VFD manufacturer shall provide the following quality assurance steps within his factory:
a) Incoming inspection of all components.
b) In-process inspection of assemblies.
c) Quality Assurance program that meets or exceeds D.O.D. Standards Audit MIL-45208.
d) MIL STD-105D AQL 1% sampling.
e) MIL STD-C45662 calibration.
f) 100% test and inspection of power devices.
2. The VFD printed circuit boards shall be tested at 50 C for 50 hours. The VFD manufacturer shall provide certification that the tests have been completed.
3. The completed VFD shall be operated on an unload motor of suitable horsepower rating.
PART 3 - EXECUTION
06 INSTALLATION
A. Install the drives where shown on the Contract Documents and in accordance with the manufacturers written instructions. Comply with NEMA Standards and requirements of the NEC.
07 START-UP
A. The Contractor shall include in his Bid the services of a factory trained representative for whatever period of time, assuming 2 trips, is required to inspect, start-up, test the system.
08 FACTORY CERTIFICATION TEST
A. Prior to final approval, the manufacturer shall submit a letter certifying that the installation has been tested and functions as required for a complete operation system.
09 SPARE PARTS
A. The following spare parts shall be furnished.
1. Three of each type of fuse rated 600V or less.
2. Two of each type of fuse rated 2.3KV or greater.
3. Four of each type of power bridge diode.
4. Two of each type of converter SCR.
5. One of each type of inverter SCR.
6. Five of each type of panel lamp.
7. One of each type of printed circuit board, including diagnostic systems.
B. If additional (seriesed) SCR's must be added to the power bridges to achieve the five-year warranty required in Paragraph 1.04, B., the quantity of spare SCR's listed in 3.04, A.4 and .5 are to be doubled.
C. A spare parts list including original device manufacturer's part numbers for cross-referencing purposes shall be furnished. Lists containing only the VFD manufacturer's part numbers are not acceptable.
3.02 WARRANTY SERVICE
A. VFD vendor shall provide 8 hour guaranteed response on-site over the warranty period.
3.03 TRAINING
A. Training shall be provided for Owner personnel. This training shall consist of both classroom based instruction and on-site instruction.
END OF SECTION
