26 29 23.pdf

Design Criteria/Facility Standards Manual Page 1 University of Maryland, College Park

Description:

The purpose of the section is to highlight the current applicable UMCP Design Standards for the design and performance of VFDs at the campus.

Related Sections:

• TBD

Effective Date:

July 10, 2009

Applicable Standards:

• 2017 NEC

• UL – Underwriters Laboratories

• IEEE 519

• NEMA ICS 7

• NEMA ICS 61800-2

• UL 61800-5-1

• NEMA MG1

General Requirements:

• Basis of Design for Drives Shall be ABB Series ACH-580. Acceptable Drives shall be by ABB (series

ACH-580), York (Series AYK) or Danfoss (Series HVAC). Where specific Model numbers are required, information shall be as directed by the university. All interior drives shall be NEMA 12 rated, exterior installed VFD’s shall be rated for application. Drives shall not be installed within Air streams.

• Variable speed drives are preferred on motors 3 horsepower and greater. Use of electric initiated integrated manufacturer option Bypasses are to be used only for specific purpose as agreed to by owner. Bypass integration when used shall be integrated into UMD CCMS.

• Motors used in conjunction with variable speed drives shall be the inverter duty type with a shaft grounding ring at the Drive end and ceramic bearing installed on the Motor end where motor HP is at or above 40 HP. Shaft grounding rings alone shall be used where less than 40 HP for all three Phase motors using VFD applications.

• Drives shall be furnished by the mechanical contractor and installed by the electrical contractor.

• Control Frequency Drives shall be manufactured by a single contractor utilizing a sine coded pulse width modulated invertor control. The variable speed drive units applied to various HVAC systems shall be provided with designs utilizing the following basic criteria/specifications:

• Converter shall consist of a modular assembly consisting of a diode rectifier and capacitor assembly which will first convert, then filter and maintain a fixed DC voltage source from the fixed voltage and frequency input.

• Invertor shall be Insulated Gate Bipolar Transistor (IGBT) with a minimum rating of 1000 VDC on 460 VAC controls to invert the converter fixed DC voltage into a sine-coded pulse with modulated output.

• Control Logic to consist of a single printed circuit board for all horsepower sizes and incorporates an 8 bit, or larger, microcomputer central processing unit to control all invertor, converter, base drive, and external interface functions.

• The VFD unit shall allow application onto systems which employ any NEMA-B induction squirrel cage motor (all new motors specified shall be inverter duty rated per NEMA MG1).

• The selected VFDs shall provide user friendly diagnostics clearly displayed at a front display.

• The following identifies the minimum features to be noted in a design:

• Standard line input voltage 460 VAC.

Design Criteria/Facility Standards Manual Page 2 University of Maryland, College Park

• Shall not induce voltage line notching into the utility line.

• The VFD units shall have native BACnet compatible programming.

• Programmable I/O

• Fault/status points

• Runtime & energy

• See Division 25 CCMS DCFS for hard wired points and additional programming during installation.

• The VFD shall be UL approved.

• Verify with manufacturer if interlock between local disconnect and VFD is required for protection of the

VFD.

• The VFD shall be designed to meet power line transient conditions defined within IEEE-587.

• Provide output reactor or dV/dt filter where motor lead length exceeds manufacturer recommendations.

• Designer to evaluate overall building distribution system and evaluate 12 Pulse drives or 6 Pulse drives with Ultra-Low Harmonic (ULH) filter as applicable based on preponderance of building services that utilize non-linear loads (i.e. UPS, VFD’s on Large Motors, etc.).

• The VFD shall comply with 2017 NEC.

• The VFD shall contain the following general features:

• Automatic restart after power outage and fault occurrences of over current or over voltage.

• Control follower circuit board to utilize 4-20 mA control signal.

• Electronic overload protection.

• Hand/Off/Auto operator switch.

• Instantaneous electronic trip when 180% FLA sensed, phase to phase output short or phase to ground output short circuit occurs. Note: Modify for motors over 100 HP based on coordination study as applicable.

• Interface for time clock control.

• Line circuit breaker.

• Manual bypass (door interlocked) for fixed 60 Hz operation in emergency.

• Speed Feedback Device.

• Minimum/Maximum adjustable speeds.

• Over-temperature protection.

• Panel mounted display of status, frequency, and service diagnostics.

• Run/Stop command switch.

• Shall provide for 100% current limit.

• Thermal overload relay.

• Timed acceleration and deceleration for soft starting and stopping.