Facilities and Services Home > Planning and Project Management > PPM Design Standards > SECTION 16160


1.1 General

A. Division 16 Basic Electrical Materials and Methods section applies to work specified in this standard.

B. Manufacturers: Only firms regularly engaged in the manufacture of variable speed drives of types, ratings, and characteristics required, whose products have been in satisfactory use in similar service for not less than five (5) years should be considered. Acceptable manufacturers include: Magnatek, Reliance, Saftronics, Square D, or others as determined by the University of Rochester representative responsible for the project.

C. The drive specification shall clearly state which equipment vendor (driven load, motor, variable speed drive) has the overall responsibility for coordinating all parts of the system.

D. A manual or automatic bypass switch should only be applied on critical loads that do not have any backup. The Operations and Maintenance Division and the Engineer shall determine this need together. Should a manual or automatic bypass feature be required, components and circuiting shall be installed per attached sketch VSD-1.

E. The Engineer should carefully specify drives in lab environments sensitive to radiated noise or to AC line noise. Install filters, isolation transformers or line reactors at the drive input, when necessary, to minimize propagation of harmonics in the building power system.

F. Internal drive control shall be fully digital and field programmable without external hardware.

G. The drive shall be fully functionally tested before shipment.

H. Submitted and as-built record documentation shall include:

1. Detailed power and control/logic wiring diagram for each variable speed drive.
2. A list of all factory and field set point values.
3. Three sets of complete installation, operation, troubleshooting and maintenance manuals.

2.1 Variable Speed Drives

A. The variable speed drive shall produce an adjustable AC voltage/frequency output for complete motor speed control using transistorized sinecoded PWM technology. Other variable speed drive technology may be considered, but it must prove equal to PWM technology.

B. Variable Speed Drives: Each drive shall have the following factory installed features:

1. Fusible disconnect switch

2. If required, bypass contactor and circuitry shall provide for complete isolation of the drive from the electrical supply for maintenance procedures. Bypass circuitry shall also provide for the manual transfer from the drive/off/bypass switch control of the motor to full speed across the line operation in the event of a variable speed drive fault.

3. Protective circuitry for:

a. over/undervoltage on any phase
b. loss of any phase
c. line notches over 5%
d. surges over 10%
e. overcurrent
f. over frequency
g. over temperature
h. line-to-line and line-to-ground output short circuit protection in both running and starting modes.

4. Automatic restart at preset conditions after a power failure, drive fault or external fault.

5. Independently adjustable acceleration and deceleration.

6. Controls/Indicators:

a. VSD/Bypass/Off/Auto Operator switch
b. Local/remote speed control operator switch
c. Drive output speed indicator (0% to 110% speed)
d. Minimum and maximum frequency adjustment
e. Selected frequency skip adjustment
f. Elapsed run time meter
g. Power on indication
h. Drive fault indication with dry contact
i. Motor run indication with dry contact

7. Electrical noise:

a. Distortion and notching less than 10% when tested in accordance with IEEE #519
b. EMI less than 50 MV at 3 feet when tested with a suitable field strength meter

8. Drive Output:

a. Linear with respect to input signal
b. Accurate to +/- 1% of speed indication
c. Stabilized to +/- 1% at constant input load
d. Repeatable to +/- 0.5% at any controller setting within the normal operating range
e. Normal operating range to be 5% to 110% of rated motor speed

9. Isolated follower for 4 - 2OmA, 0 - 10 VDC signal, direct or reverse acting selectable.

10. Minimum 18,000 A.I.C. rating

11. Drive must be able to start into a rotating load, both forward and reverse, without

12. The drive must be self contained and totally enclosed in an appropriate NEMA cabinet (minimum NEMA 1).

13. Drive must operate at a minimum power factor of .95 over the entire operating range regardless of speed and load.

14. Drive must shut down as a result of a signal generated from a remote set of dry contacts, i.e. freeze or fire alarm.

15. If required drive must be able to force fan operation to 100% capacity as a result of a signal generated from a remote set of dry contacts, i.e. and engineered smoke removal system. This option may be implemented through the drive or through the bypass.

16. See illustration below for further clarification.



These Design Standards were last modified January 2003.