HEATING, VENTILATING & AIR CONDITIONING 
VARIABLE FREQUENCY DRIVES
PART 1 - 	GENERAL
1.01	DESCRIPTION
A.	This specification is to cover a complete Variable Frequency Drive (VFD) consisting of a pulse width modulated (PWM) inverter designed for use with a permanent magnet direct drive motor.
B.	The cooling tower manufacturer must supply the VFD and all necessary options as herein specified.  
1.02	QUALITY ASSURANCE
A.	Referenced Standards and Guidelines:
1.	IEEE 519-1992, Guide for Harmonic Content and Control.
2.	UL508(A)(C) - Underwriter's Laboratory
3.	ICS 7.0, AC Adjustable Speed Drives
4.	EN/IEC 61800-3
5.	NEC 430.120, Adjustable-Speed Drive Systems
6.	IBC 2018 Seismic – referencing ASC 7-05 and ICC AC-156
7.	VFD manufacturing facility must be ISO 9001 and ISO 14001 certified.
8.	CAN/CSA-C22 No. 14-M91 - Canadian Standards Association
B.	Qualifications:
1.	VFDs and options must be UL508 listed as a complete assembly.  The base VFD must be UL listed for 100 kA SCCR without the need for external input fuses.
2.	CE Mark – The base VFD must meet product standard EN 61800-3 for the First Environment restricted level (Category C2).  (RFI / EMI Filter spec).
3.	NEMA 1 Enclosure Only: The entire VFD assembly must be seismically certified and labeled as such in accordance with the 2018 International Building Code (IBC):
a.	VFD manufacturer must provide Seismic Certification and Installation requirements at time of submittal.
b.	Seismic importance factor of 1.5 rating is required, and must be based upon actual shake test data as defined by ICC AC-156.
c.	Seismic ratings based upon calculations alone are not acceptable. Certification of Seismic rating must be based on testing done in all three axis of motion by a certified lab.
d.	Special seismic certification of equipment and components must be provided by OSHPD preapproval.
1.03	SUBMITTALS
A.	Submittals must include the following information:
1.	Outline dimensions, conduit entry locations and weight.
2.	Customer connection and power wiring diagrams.
3.	Complete technical product description include a complete list of options provided.  
1.04	BUILDING INFORMATION MODELING (BIM)
A.	BIM objects must contain IFC parameters and associated data applicable to building system requirements. These elements must support the analytic process including size, clearance, location, mounting heights, and system information where applicable. 
PART 2 - 	PRODUCTS
2.01	VARIABLE FREQUENCY DRIVES
A.	The VFD package as specified herein and defined on the VFD schedule must be enclosed in a UL Type enclosure (enclosures with only NEMA ratings are not acceptable). 
1.	Environmental operating conditions: -15 to 40° C (5 to 104° F) continuous. Altitude 0 to 3300 feet above sea level, less than 95%, non-condensing. All circuit boards must be coated to protect against corrosion.
2.	The VFD must be rated to operate from 3-phase power at 208 VAC to 240 VAC +10/-10% / 380 VAC to 500 VAC +10/-10% / 525 to 690 VAC (600 VAC, UL and CSA) +10/-10%. The overvoltage trip level must be a minimum of 30% over nominal, and the undervoltage trip level must be a minimum 35% under the nominal voltage.
3.	Keypad with USB connection. 
4.	The VFD will have a cooling tower specific setup wizard that quickly configures the appropriate parameters for use with a cooling tower.  Setup wizard options will include a de-ice function, motor preheat function, vibration switch setup. Selection will be offered for both 2-wire and 3-wire start/stop control.
B.	All VFDs must have the following standard features.
1.	All VFDs must have the same customer interface, including digital display, and keypad, regardless of horsepower rating.  The keypad must be removable, capable of remote mounting and allow for uploading and downloading of parameter settings as an aid for start-up of multiple VFDs. 
2.	Graphical Multilingual Display: Graphical metering and trending will be shown on keypad. Display will also include intelligent startup assistant, motor ID run and direct Torque Control (DTC) for accurate control of a permanent magnet motor.
3.	The five (5) active and most recent fault messages and times must be stored in the VFD’s fault history.
4.	The keypad must include speed control and start / stop.  There must be fault reset and “Help” buttons on the keypad.  The Help button must provide assistance for programming and troubleshooting.  
5.	VFDs must have internal chokes (reactors) providing 3% impedance to reduce the harmonics to the power line and to add protection from AC line transients.
6.	The input current rating of the VFD must not be greater than the output current rating.  VFD’s with higher input current ratings require the upstream wiring, protection devices, and source transformers to be oversized per NEC 430.122
C.	All VFDs to have the following adjustments:
1.	Run permissive circuit - There must be a run permissive circuit for damper or valve control.  Regardless of the source of a run command (keypad, input contact closure, time-clock control, or serial communications), the VFD must provide a dry contact closure that will signal the damper to open (VFD motor does not operate).  When the damper is fully open, a normally open dry contact (end-switch) must close.  The closed end-switch is wired to a VFD digital input and allows VFD motor operation.  Two separate safety interlock inputs must be provided.  When either safety is opened, the motor must be commanded to coast to stop and the damper must be commanded to close. 
2.	VFD will be pre-programmed to include multiple safety circuits to prevent VFD and motor operation upon loss of a safety signal. Safety circuits for vibration switch and motor thermostat are included as standard. 
3.	All safeties need to be individually landed on the VFD. Each safety must be annunciated with an English language description of the fault when the safety opens. Alarm examples include “Vibration Switch” and “Motor Thermostat Open”. 
a.	The VFD must include a fireman’s override input.  The mode must provide a safe torque off (STO) the Safe Torque Off (STO) function disables the control voltage of the power semiconductors of the VFD output stage, thus preventing the VFD from generating the torque required to rotate the motor. If the motor is running when Safe torque off is activated, it coasts to a stop.
D.	Serial Communications
1.	The VFD must have an RS-485 port as standard.  The standard protocols must be Modbus RTU. 
2.	(Optional) BACnet MSTP and Ethernet / IP is provided via BACnet Gateway. Gateway to be field installed by others for NEMA-1 enclosure and factory installed for NEMA-12 and NEMA-3R enclosures. 
3.	All protocols must be “certified” by the governing authority (i.e. BTL Listing for BACnet).  
E.	EMI / RFI filters.  All VFD’s must include EMI/RFI filters.  The onboard filters must allow the VFD assembly to be CE Marked and the VFD must meet product standard EN 61800-3 for the First Environment restricted level (Category C2).
F.	VFD OPTIONS – Options must be furnished and mounted by the VFD manufacturer as defined on the VFD schedule.  All optional features must be UL Listed by the VFD manufacturer as a complete assembly and carry a UL508 label.
PART 3 - 	EXECUTION
3.01	INSTALLATION
A.	Installation must be the responsibility of the mechanical contractor.  
B.	Power wiring must be completed by the electrical contractor, to NEC code 430.122 wiring requirements based on the VFD input current.  
C.	The contractor must complete all wiring in accordance with the recommendations of the VFD manufacturer as outlined in the installation manual.
3.02	START-UP
A.	Factory startup must be provided for each VFD by a factory authorized personnel.  
3.03	PRODUCT SUPPORT
A.	Factory trained application engineering and service personnel that are thoroughly familiar with the VFD products offered must be locally available at both the specifying and installation locations.  A toll free 24/365 technical support line connected to factory support personnel located in the US must be available. Technical support offered only through the local sales office is not acceptable.
3.04	WARRANTY
A.	The VFD Product Warranty must be 5 years from the date of factory shipment. The warranty must include parts only.

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