Sorvall TC6 User manual
Service Manual
SORVALL
TC6
Parts Section
Updated March '02
IMPORTANT INFORMATION REGARDING USE OF THIS MANUAL
READ BEFORE USING
This manual provides technical information for the proper servicing of the product(s) specified. This manual is
intended only for use by Sorvall Service personnel, or by qualified technicians who have been trained by Sorvall
in the safe, proper servicing of that product.
This manual has been designed as a supplement to training, not a substitute for training; servicing should not
be attempted by untrained personnel. Technicians who have not been trained by Sorvall are not familiar with the
product design or the hazards that may be encountered during servicing. In addition, lack of training can result
in faulty repair – possibly making subsequent product use dangerous, or product yields unreliable.
Although content of this manual is believed to be adequate for its intended use, Sorvall makes no representation or warranty regarding completeness, adequacy or otherwise (not even as a supplement to a given training
course) and assumes no obligation or liability. In the event a qualified, trained technician is unable to repair the
product using this manual, Sorvall Technical Service should be contacted for additional guidance.
OPERATING
INSTRUCTIONS
SORVALL TC6
Tabletop
Centrifuge
Sorvall Products, L.P.
Newtown, Connecticut
U.S.A.
PN 78006-1
Issued August 1996
Table of Contents
This manual is a guide for service of the
SORVALL Centrifuges
SORVALL TC6 Tabletop Centrifuge
Data herein has been verified and validated and is believed adequate for the intended use of the
centrifuge. Because failure to follow the recommendations set forth in this manual could produce
personal injury or property damage, always follow the recommendations set forth herein. Sorvall does
not guarantee results and assumes no obligation for the performance of rotors or other products that are
not used in accordance with the instructions provided. This publication is not a license to operate under,
nor a recommendation to infringe upon, any process patents.
This service manual is intended as a service aid. While the manual is kept current and includes
information regarding significant design changes, specific designs may still vary from centrifuge to
centrifuge.
This service manual is intended for use only by service personnel who have been trained by Du␣Pont.
Due to the high electrical potential in this centrifuge, untrained individuals must not attempt any of the
procedures in this service manual.
WARNINGS, CAUTIONS, and NOTES within the text of this manual are used to emphasize important
and critical instructions:
WARNING
: A Warning informs the operator of a hazard or an unsafe practice that could result in
personal injury, affect the operator's health, or contaminate the environment.
CAUTION:
NOTE:
A Caution informs the operator of an unsafe practice that could result in damage of
equipment.
A Note highlights essential information.
W A R N I N G
!
When using radioactive, toxic, or pathogenic material, be aware of all characteristics of the material and
the hazards associated with it. In the event that leakage or rotor failure occurs, neither the centrifuge nor the rotor
can protect you from the particles dispersed into the air. To protect yourself, we recommend additional precautions
be taken to prevent exposure to these materials, for example, controlled ventilation or isolation. DO NOT USE
MATERIALS CAPABLE OF PRODUCING FLAMMABLE OR EXPLOSIVE VAPORS.
© 1996 by Sorvall Products, L.P.
ii
®
TC6
Table␣ of␣ Contents
Paragraph Page
Section 1.␣ ␣ ␣ INTRODUCTION and DESCRIPTION
1-1. Intended Use of Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
1-2. Service Decontamination Policy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
1-3. Warranty Responsibility. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
1-4. Centrifuge Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
1-5. Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
1-6. Controls, Displays, Switches and Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
Section 2.␣ ␣ INSTALLATION and OPERATION
Table of Contents
2-1. Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
2-2. Preinstallation Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
2-3. Electrical Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
2-4. Voltage Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
2-5. Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4
2-6. Rotor Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4
2-7. Running Hazardous Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5
2-8. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
2-9. Emergency Sample Recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7
Installation Checklist
Section 3. SYSTEM DESCRIPTIONS
3-1. General System Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
3-2. Power System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2
3-3. Drive Motor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2
3-4. Brushless Motor Drive Electronics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2
3-5. Speed Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6
3-6. Timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7
3-7. Door Latching Mechanism. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7
Section 4. PRINTED CIRCUIT BOARDS and
SCHEMATIC DIAGRAMS
iii
Table of Contents
Table␣ of␣ Contents (continued)
Paragraph Page
Section 5. REPAIR and REPLACEMENT
5-1. Latch Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
5-2. Latch Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2
5-3. Door Latched Microswitch Adjustment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4
5-4. Hinge Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5
5-5. Door Closed Sensor Check. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-6
5-6. Door Closed Sensor Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-6
5-7. Fuse Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-8
5-8. Precautions for Handling of Printed Circuit Boards . . . . . . . . . . . . . . . . . . . . . . . 5-9
5-9. Printed Circuit Board Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-9
5-10. Motor Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-10
5-11. Fan and Grille Replacement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-11
5-12. Power Connector Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-13
5-13. Speed Potentiometer Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-15
SORVALL Centrifuges
Section 6. TROUBLESHOOTING
Section 7. MAINTENANCE
7-1. Routine Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1
7-2. Preventive Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-3
Preventive Maintenance Checklist
Section 8. ILLUSTRATED PARTS
iv
TC6
®
Table of Contents
List of Tables
Table Page
1-1. Description of Controls, Displays, Switches and Indicators . . . . . . . . . . . . . . . . 1-6
4-1. Component Description, Control Printed
Circuit Board, PN 78189 Rev. 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-11
4-2. Component Description, Display Printed
Circuit Board, PN 78178 Rev. 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-17
4-3. Component Description, Display Printed
Circuit Board, PN 78178 Rev. 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-23
4-4. Component Description, Power Supply Printed
Circuit Board, PN 78049 Rev. 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-26
4-5. Component Description, Power Supply Printed
Circuit Board, PN 78049 Rev. 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-29
4-6. Component Description, Power Supply Printed
Circuit Board, PN 78049 Rev. 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-32
4-7. Component Description, Motor Control Printed
Circuit Board, PN 78230 Rev. 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-36
4-8. Component Description, Motor Control Printed
Circuit Board, PN 78230 Rev. 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-42
4-9. Component Description, Motor Control Printed
Circuit Board, PN 78230 Rev. 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-48
6-1. TC6® Troubleshooting Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
8-1. Parts: TC6® Main Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-3
8-2. Parts: TC6® Chassis Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-5
List of Illustrations
Figure Page
1-1. TC6® Controls and Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
2-1. Voltage Selection (SN 9501733 and below) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3
2-2. Location of Mechanical Override . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7
4-1. System Wiring Diagram, Rev. 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
4-2. System Wiring Diagram, Rev. 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5
4-3. Schematic for Control Printed Circuit Board, PN 78189 Rev. 3 . . . . . . . . . . . . . . 4-7
4-4. Control Printed Circuit Board Assembly, PN 78189 Rev. 3 . . . . . . . . . . . . . . . . . 4-9
4-5. Schematic for Display Printed Circuit Board, PN 78178 Rev. 4 . . . . . . . . . . . . . . 4-13
4-6. Display Circuit Board Assembly, PN 78178 Rev. 4 . . . . . . . . . . . . . . . . . . . . . . . . 4-15
4-7. Schematic for Display Printed Circuit Board, PN 78178 Rev. 2 . . . . . . . . . . . . . . 4-19
4-8. Display Printed Circuit Board Assembly, PN 78178 Rev. 2 . . . . . . . . . . . . . . . . . 4-21
4-9. Schematic for Power Supply Printed Circuit Board, PN 78049 Rev. 4 . . . . . . . . 4-24
4-10. Power Supply Printed Circuit Board Assembly, PN 78049 Rev. 4. . . . . . . . . . . . 4-25
4-11. Schematic for Power Supply Printed Circuit Board, PN 78049 Rev. 2 . . . . . . . . 4-27
4-12. Power Supply Printed Circuit Board Assembly, PN 78049 Rev. 2. . . . . . . . . . . . 4-28
4-13. Schematic for Power Supply Printed Circuit Board, PN 78049 Rev. 1 . . . . . . . . 4-30
v
Table of Contents
SORVALL Centrifuges
List of Illustrations (continued)
Figure Page
4-14. Power Supply Printed Circuit Board Assembly, PN 78049 Rev. 1. . . . . . . . . . . . 4-31
4-15. Schematic for Motor Control Printed Circuit Board, PN 78230 Rev. 4 . . . . . . . . 4-33
4-16. Motor Control Printed Circuit Board Assembly, PN 78230 Rev. 4 . . . . . . . . . . . 4-35
4-17. Schematic for Motor Control Printed Circuit Board, PN 78230 Rev. 4 . . . . . . . . 4-39
4-18. Motor Control Printed Circuit Board Assembly, PN 78230 Rev. 4 . . . . . . . . . . . 4-41
4-19. Schematic for Motor Control Printed Circuit Board, PN 78230 Rev. 0 . . . . . . . . 4-45
4-20. Motor Control Printed Circuit Board Assembly, PN 78230 Rev. 0 . . . . . . . . . . . 4-47
5-1. Latch Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2
5-2. Door Closed Sensor Parts Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-7
5-3. Fuse Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-9
5-4. Fuse Replacement/Voltage Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-9
5-5. Reinstalling the Cabinet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-14
8-1. TC6® Main Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-2
8-2. TC6® Chassis Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-4
vi
®
TC6
Contents
Section 1. Introduction and Description
1.1. Intended Use of Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
1-2. Service Decontamination Policy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
1-3. Warranty Responsibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
1-4. Centrifuge Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
1-5. Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
1-6. Controls, Displays, Switches and Indicators . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
Table of Contents
Page
vii
®
TC6
Introduction and Description
Section 1: INTRODUCTION and␣ DESCRIPTION
This manual is a service guide for the SORVALL® TC6® Tabletop Centrifuge. It contains descriptive
information, repair and replacement procedures, schematics, troubleshooting, calibrations, and an
illustrated parts list for ordering replacement parts.
1-1. Intended Use of Manual
W A R N I N G
!
To avoid personal injury, all
replacement and calibration procedures should be performed by qualified service personnel.
W A R N I N G
!
Because of the characteristics of the samples likely to be processed in this centrifuge, biological
or radioactive contamination may occur. Always be aware of this possibility, and take normal precautions. Use
appropriate decontamination procedures should exposure occur.
This manual is for qualified service personnel who are familiar with
factory methods for performing repairs, adjustments and calibrations.
Warnings, Cautions, and Notes are used throughout this manual to
emphasize important and critical instructions. Service personnel
are expected to be familiar with their meaning (see page ii) and to
read them before servicing the centrifuge.
1-2. Service Decontamination
Policy
If a centrifuge or rotor that has been used with radioactive or
pathogenic material requires servicing by Sorvall personnel, either
at the customer’s laboratory or at a Sorvall facility, comply with the
following procedure to ensure the safety of all personnel:
1. Clean the centrifuge or rotor to be serviced of all encrusted
material and decontaminate it prior to servicing by the Sorvall
representative or returning it to the Sorvall facility. There must
be no radioactivity detectable by survey equipment.
The SORVALL® Rotors, Tubes, Bottles, Adapters and Accessories Catalog contains descriptions of commonly used decontamination methods and a chart showing method compatibility
with various materials. This service manual contains specific
guidance about cleaning and decontamination methods appropriate for the centrifuge or rotor it describes (see paragraph 7-1).
Clean and decontaminate your centrifuge or rotor as follows:
For TC6
a. Remove rotor from the rotor chamber.
b. Remove motor cover and wash with appropriate
c. Decontaminate door, rotor chamber, chamber door seal,
®
tabletop centrifuges:
decontaminant.
and drive, using an appropriate method.
1-1
Introduction and Description
SORVALL Centrifuges
For rotors:
Remove tubes, bottles, and adapters from the rotor and
decontaminate rotor using an appropriate method. If tubes
or rotor caps are stuck in the rotor, or the rotor door is stuck,
notify Sorvall representative; be prepared with the name
and nature of the sample so the Sorvall Chemical Hazards
Officer can decide whether to authorize the rotor's return to
a Sorvall facility.
2. Complete Decontamination Information Certificate (SORVALL
products Form No. IPDP-59 or E53603) and attach it to the
centrifuge or rotor before servicing or returning to Sorvall facility. Certificates are included in the back of this manual. Additional certificates are available from the local Account Representative or Field Service Engineer. In the event that these
certificates are not available, it will be acceptable to include a
written statement certifying that the unit has been properly
decontaminated and outlining the procedures used.
If the centrifuge or rotor must be returned to a Sorvall facility:
1. Contact your Sorvall representative to obtain a Return Service
Order Number (RSO No.). Be prepared with the name and
serial number of the centrifuge or rotor and the repairs required.
2. Send item(s) with the RSO No. clearly marked on the outside
packaging to the address obtained from your Sorvall representative.
NOTE
United States federal regulations require that parts and
centrifuges
ported. Outside the United States, check local regulations.
must
be decontaminated before being trans-
®
1-2
If a centrifuge or rotor to be serviced does not have a
Decontamination Information Certificate attached and, in Sorvall's
opinion presents a potential radioactive or biological hazard, the
Sorvall representative will not service the equipment until proper
decontamination and certification is complete. If Sorvall receives a
centrifuge or rotor at its Service facilities which, in its opinion, is a
radioactive or biological hazard, the sender will be contacted for
instructions as to disposition of the equipment. Disposition costs
will be borne by the sender.
NOTE
The Field Service Engineer will note on the Customer
Service Repair Report if decontamination was required
and, if so, what the contaminant was and what procedure was used. If no decontamination was required, it
will be so stated.
TC6
®
Introduction and Description
1-3. Warranty Responsibility
Whenever service of the centrifuge is attempted by anyone other
than an employee of Sorvall or an authorized representative, the
individual is assuming the risk of voiding the centrifuge warranty,
which is as follows:
Sorvall Products, L.P. makes no warranty of any kind, expressed or
implied, except as stated in this warranty policy.
The SORVALL® TC6® Tabletop Centrifuge is warranted to be free
from defects in materials and workmanship for a period of one year
from the date of delivery. Sorvallwill repair or replace and return
free of charge any part which is returned to its factory within said
period, transportation prepaid by user, and which is found upon
inspection to have been defective in materials or workmanship.
This warranty does not apply to any damage to any instrument
resulting from: normal wear and tear; misuse; abuse; use of electrical currents or circuits other than those specified on the plate affixed
to the instrument; or use of any rotor other than those intended for
use in this instrument.
Sorvall reserves the right to change, alter, modify or improve any of
its instruments without any obligation whatsoever to make corresponding changes to any instrument previously sold or shipped.
The foregoing obligations are in lieu of all other obligations and liabilities
including negligence and all warranties, of merchantability or otherwise,
expressed or implied in fact or by law, and state our entire and exclusive
liability and buyer's exclusive remedy for any claim or damages in connection with the sale or furnishing of goods or parts, their design, suitability
for use, installation or operation. Sorvall will in no event be liable for any
special or consequential damages, and our liability under no circumstances will exceed the contract price for the goods for which liability is
claimed.
1-3
Introduction and Description
SORVALL Centrifuges
1-4. Centrifuge Description
The TC6® is a lowspeed, non-refrigerated tabletop centrifuge that
features digital readout displays, a dc brushless (maintenance free)
motor, a closed-loop speed control, a removable stainless steel rotor
chamber, ergonomically designed front panel control knobs and
switches, and has a see-through chamber door that allows rotor
calibration and visual inspection of a run in progress. The chamber
door is counterbalanced for easy opening and safe closing. The
door latch automatically locks when the chamber door is closed
and an interlock prevents the chamber door from being opened
during operation.
1-5. Specifications
Maximum Operating Speed: . . . . . . . . 6000 rpm*
Maximum heat output
during operation: . . . . . . . . . . . . . . . . . 650 Btu/hour (190 Watts)
Electrical Requirements: . . . . . . . . . . . . 100 - 120 Vac, 60Hz,
3.15A, single phase
220 - 240 Vac, 50 Hz,
2A, single phase
Dimensions:
Width . . . . . . . . . . . . . . . . . . . . . . . . . . . 39.4 cm (15.5 inches)
Depth . . . . . . . . . . . . . . . . . . . . . . . . . . . 55.9 cm (22.0 inches)
Height . . . . . . . . . . . . . . . . . . . . . . . . . . . 26.7 cm (10.5 inches)
Height (with door open) . . . . . . . . . . . 78.7 cm (31.0 inches)
Mass (Weight): . . . . . . . . . . . . . . . . . . . . . 31 kg (70 lbs)
Decibel Level: . . . . . . . . . . . . . . . . . . . . . <60 dB at 3500 rpm
Operating Temperature Range: . . . . . . 10°C to 35°C
(50°F to 95°F)
Relative Humidity
(Normal Operating Range): . . . . . . . . 20% to 70%
1-4
*Speed in revolutions per minute (rpm) is related to angular velocity, ω, according to the
following:
ω
= (rpm) = (rpm) (0.10472)
Where ω = rad/s. All further references in this manual to speed will be designated as rpm.
(
2π
60
)
TC6
®
Introduction and Description
1-6. Controls, Displays,
Switches and Indicators
Figure 1-1 shows the TC6® control panel and provides a brief description for each control, display, switch and indicator. Table 1-1
(on the next page) gives a complete description.
SPEED DISPLAY
Displays actual rotor speed
from 0 to 6000 rpm (± 1%
or 10 rpm, whichever is
greater).
SPEED DIAL
Sets desired rotor
speed.
5
1
SPEED
RPM
R
TIME DIAL
Sets length of run
time up to 99 minutes.
TIME DISPLAY
Displays set run time and,
during a run, remaining run
time.
67
2
TIME
MIN
HOLD SWITCH
Selects a continuous run.
When lit, indicates that the
chamber door is closed and
latched and that the centrifuge is ready for operation.
START SWITCH
Starts the centrifuge run.
READY INDICATOR
3
READY DOOR
8
STOP SWITCH
Stops the centrifuge run.
DOOR INDICATOR
Blinks at end of run indicating the chamber door
may be opened.
9
4
DOORSTOPSTARTHOLD
DOOR SWITCH
10
Opens the chamber door.
Figure 1-1. TC6
®
Controls and Indicators
1-5
Introduction and Description
SORVALL Centrifuges
Table 1-1. Description of Controls,
Displays, Switches and Indicators
SPEED display Indicates actual rotor speed from 0
to 6000 rpm (± 1% or 10␣rpm, whichever is greater).
TIME display Indicates set run time at the begin-
MIN
READY indicator light When lit, indicates that the chamber
DOOR indicator light At the end of the run this light blinks
ning of the run and the remaining
run time after the START switch is
pressed. In HOLD mode, two dashes
are displayed.
door is closed and latched and that
the centrifuge is ready for operation.
indicating that the rotor has stopped
spinning and that the chamber door
may be opened.
SPEED dial Sets the desired rotor speed in rpm.
As indicated by the symbol, turn the
dial to the right to increase speed.
TIME dial Sets length of run time up to 99 min-
utes.
HOLD switch Selects a continuous run (two dashes
will appear in the TIME display to
indicate a run in HOLD mode).
START switch Starts the centrifuge run.
STOP switch Stops the centrifuge run.
DOOR switch At the end of a run, after the rotor
has stopped spinning and the DOOR
light blinks, this switch releases the
chamber door.
POWER switch The power switch is a rocker switch
(NOT SHOWN)
that toggles on and off. When set to
"I", applies power to the centrifuge.
1-6
Table of Contents
Contents
Section 2. Installation and Operation
2-1. Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
2-2. Preinstallation Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
2-3. Electrical Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
2-4. Voltage Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
2-5. Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4
2-6. Rotor Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5
2-7. Running Hazardous Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
2-8. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7
2-9. Emergency Sample Recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-8
Installation Checklist
SORVALL Centrifuges
Page
viii
®
TC6
Installation and Operation
Section 2: INSTALLATION and OPERATION
This section contains information to install and operate your SORVALL TC6® Tabletop Centrifuge.
2-1. Inspection
W A R N I N G
!
The TC6® weighs 70 lbs.
Refer to the unpacking instructions
for proper care when lifting and installing the centrifuge. Failure to use
proper lifting techniques can result in
personal injury and/or possible damage to the centrifuge.
C A U T I O N
!
Do not lift the centrifuge by
the front panel or the door. To do so
can result in damage to these parts.
C A U T I O N
!
The centrifuge can be damaged if connected to the wrong voltage. Check the voltage before plugging the centrifuge into any power
source. Sorvall is not responsible for
incorrect installation.
When you receive your centrifuge, carefully inspect it for any signs
of shipping damage. If you find damage, report it immediately to
the transportation company and file a damage claim, then notify
Sorvall.
Check the parts received with the centrifuge against the shipping
list; if any parts are missing, contact Sorvall (see office list in back of
manual).
2-2.␣ Preinstallation Require-
ments
The TC6® centrifuge is ordered for a specific voltage. The nameplate
on the back of the centrifuge tells the voltage ordered. Before using
the TC6®, be sure the proper operating voltage and corresponding
fuse is selected. If required (for instruments serial number 9501733
and below), the voltage setting and fuses can be changed (refer to
page 2-2, paragraph 2-4, Voltage Selection for procedure to change
the voltage).
Other preinstallation requirements include:
• providing a flat, level surface to support the weight of the
centrifuge (31 kg; 70 lbs),
• allowing adequate space for proper air circulation (5 cm;
2␣inches),
• allowing for the proper height clearance to open the chamber
door (78.7 cm; 31.0 inches); and
• providing the proper electrical requirements.
2-1
Installation and Operation
SORVALL Centrifuges
C A U T I O N
!
If the power cord is
connected to the wrong voltage, it
can cause damage to the centrifuge.
Check the voltage listed on the
nameplate before plugging the power
cord into the power source. Sorvall is
not responsible for incorrect
installation.
2-3. Electrical Requirements
The centrifuge has specific power requirements and must be
connected to the correct power supply for proper performance. The
nameplate on the back of the centrifuge specifies one of the following:
100 - 120 Vac, 60 Hz, single phase, 3/15 amps*
220 - 240 Vac, 50 Hz, single phase, 2 amp*
Check line voltage with a voltmeter. Then, verify that the voltage
indicated on the nameplate on the back of the centrifuge agrees
with the measured line voltage.
If the line voltage is beyond the ±10% tolerance (of nominal) given,
the result can be variations in the performance specifications and
damage to the centrifuge.
The power cord has a keyed plug that inserts into a receptacle at the
back of the centrifuge. The other end of the power cord has a threeprong molded cap with a ground pin and parallel blades. (60 Hz
instruments require receptacle NEMA 5-15R and 50 Hz instruments
require NEMA 6-15 R.).
For connection to other receptacles, the power cord may have to be
replaced. Follow local electrical regulations.
Check that the gound lug of the electrical plug is properly grounded
and is shorted to the frame of the centrifuge.
2-4. Voltage Selection
(SN 9501733 and Below)
The voltage is set by the voltage selector (in the fuse block) located
in the power connector on the back of the TC6® (refer to figure 2-1
for SN 9501733 and below). The current voltage setting (100, 110**,
220, or 240) is displayed in the window of the fuse block.
To change the voltage:
1. Unplug the power cord from the wall receptacle and from the
power connector.
2. Squeeze the two tabs located on either side of the fuse block and
carefully remove the fuse block from the power connector.
2-2
NOTE
*CSA and UL Certified.
**For 120 V operation, the voltage selector is set to 110.
Voltage can only be changed on instruments with serial
numbers 9501733 and below. Instruments with serial
numbers 9501734 and above must be ordered prewired
for specific voltages.
TC6
®
Installation and Operation
SELECTED
VOLTAGE
POWER
CORD
WINDOW
POWER
CONNECTOR
Figure 2-1. Voltage Selection (SN 9501733 and below)
C A U T I O N
!
When changing the voltage
setting, be sure that the voltage
selector is installed so that the voltage
displayed in the voltage window
matches the intended input voltage.
Also, be sure that the proper fuses
have been installed, and that you are
using the proper power cord.
Incorrect installation can result in
damage to the centrifuge. Sorvall is
not responsible for incorrect
installation.
TABS
FUSES
SELECTABLE
POWER
CONNECTOR
FUSE
BLOCK
VOLTAGE
SELECTOR
VOLTAGE
WINDOW
VOLTAGES
VOLTAGE
SELECTOR
FUSE
BLOCK
3. Gently pull the voltage selector from the fuse block.
4. Rotate the voltage selector until the desired voltage is aligned
with the window in the fuse block. Then, reinstall the voltage
selector into the fuse block.
5. Check that proper fuses are installed. Fuses are Type T, 250 V,
but change amperage rating depending on the voltage selected:
• 100 or 110 setting requires two 3.15-amp fuses, (PN 91428),
• 220 or 240 setting requires two 2-amp fuses, (PN 91203).
Change fuses if necessary.
6. Reinstall the fuse block into the power connector and plug in
the centrifuge power cord.
NOTE
If the voltage was changed from 100-110 setting to 220240 setting, a different power cord is required.
2-3
Installation and Operation
SORVALL Centrifuges
2-5. Installation
C A U T I O N
!
Do not lift the centrifuge by
the front panel or the chamber door.
To do so can result in damage to
these parts.
If the power cord is connected to the
wrong voltage, it can cause damage
to the centrifuge. Check the voltage
listed on the nameplate before
plugging the power cord into the
power source. Sorvall is not
responsible for incorrect installation.
Do not operate the centrifuge without
making sure the rotor is properly
balanced. Also, when installing a
rotor, carefully place it on the
centrifuge drive spindle. The
centrifuge spindle bearings can be
damaged if rotor is dropped on the
drive spindle.
To install the centrifuge:
1. Place the centrifuge on a sturdy bench or work table that will
support its weight, leaving space for sample preparation. Be
sure to leave a minimum clearance of 10 cm (4 inches) on all
sides for proper air circulation.
2. Make sure the centrifuge is level.
3. Make sure the centifuge is set for the proper voltage (see page
2-3, Voltage Selection).
4. Make sure the power switch is set to "O" (OFF position).
5. Insert the universal keyed end of the power cord into the power
connector at the back of the centrifuge and the other end into a
wall receptacle. The centrifuge is now ready for use.
2-6. Rotor Considerations
a. Rotor Temperature
W A R N I N G
!
Blocking the air flow entering and/or exiting the TC6® centrifuge will cause an increase in temperature within the rotor chamber. The
temperature increase can temporarily
distort non-metal surfaces allowing
particles to exit the rotor chamber
resulting in personal injury and/or centrifuge damage should tube breakage or rotor failure occur.
When loading the rotor, be sure not
to exceed the maximum compartment
mass of the rotor (see the individual
rotor instruction manual). If maximum
compartment mass is exceeded,
maximum rotor speed must be
lowered as described in the rotor
instruction manual, Compartment
Loads in Excess of Design Mass.
Failure to do so can cause rotor failure
which could result in personal injury
and/or centrifuge damage.
Centrifugation creates an increase in rotor temperature. The increase
in temperature is caused by variables including rotor speed, length
of the run, and the type of rotor.
Air flow through the TC6® Centrifuge is designed to minimize the
increase in rotor temperature. Air enters through the air vent in the
front panel and exits through the fan vent located at the back of the
centrifuge.
When running temperature-sensitive material, a trial run is
recommended.
b. Rotor Installation, Loading and Balancing
Before placing the rotor on the drive spindle, make sure that there
are no loose objects inside the rotor chamber; for example, clips,
tubing, tape, or labels, and that the rotor centerhole and drive
spindle are clean and free of nicks and scratches. Wipe these surfaces
before each use.
Gently place the rotor body on the tapered spindle of the centrifuge,
aligning the shaft pin with the slots in the rotor. Secure the rotor to
the drive spindle by turning the rotor locking knob clockwise.
2-4
TC6
®
Installation and Operation
C A U T I O N
!
Do not operate the centrifuge without making sure the rotor is
properly balanced. Also, when installing a rotor,
centrifuge drive spindle. The centrifuge drive spindle bearings can be
damaged if the rotor is dropped on
the drive spindle.
carefully
place it on the
W A R N I N G
!
When using radioactive,
toxic, or pathogenic materials, be
aware of all characteristics of the
materials and the hazards associated
with them in the event leakage occurs during centrifugation. If leakage
does occur, neither the centrifuge nor
the rotor can protect you from particles dispersed in the air. To protect
yourself, we recommend additional
precautions be taken to prevent exposure to these materials, for example, use of controlled ventilation
or isolation areas.
Always be aware of the possibility of
contamination when using radioactive, toxic, or pathogenic materials.
Take all necessary precautions and
use appropriate decontamination procedures if exposure occurs.
NOTE
The rotor locking knob cannot be tightened if the rotor is
not properly installed on the drive spindle.
Refer to the rotor instruction manual for bucket loading and balancing procedures as well as information regarding the selection and
use of tubes, bottles, and adapters.
2-7. Running Hazardous
Material
Because the centrifuge chamber of the TC6® is not designed for
biocontainment, some vapors or aerosols released from uncapped,
leaking or broken tubes may leak from the chamber during operation.
Once a run is completed and the chamber door is opened, the
vapors or aerosols which have concentrated in the chamber will be
released into the laboratory area. For this reason, when materials
which are radioactive, pathogenic, toxic, or otherwise hazardous in
nature are to be run, the centrifuge should be located in a biohazard
safety enclosure and operated using all appropriate safety
precautions. If desired, we recommend the use of sealed bucket
assembly (Catalog No. 78016) to offer increased protection from
contamination from uncapped, leaking or broken tubes.
NOTE
The sealed bucket assemblies (Catalog No. 78016) are
designed to seal tightly during operation and meet the
British Standards BS 4402:1982 Appendix D. They have
been tested at the Public Health Laboratory Service
Centre for Applied Microbiology and Research, Porton
Down, United Kingdom, and found suitable for use with
materials up to ACDP Category 3.
The use of sealed rotors, buckets and/
or sample containers will provide increased protection from contamination during routine operation. However, these items will not guarantee
contamination protection from accidents resulting in damage to the rotor
or buckets. Do not run hazardous material in the centrifuge unless it is
placed in a biohazard enclosure and
operated using appropriate safety precautions.
Use appropriate decontamination procedures should exposure to
any hazardous material occur. Read paragraph 1-2, page 1-1 for the
procedure to follow if a centrifuge or rotor that has been used with
a hazardous material must be returned to our service facilities for
repair.
2-5
Installation and Operation
SORVALL Centrifuges
2-8. Operation
W A R N I N G
!
Be sure the rotor chamber
and chamber door gasket are installed
before the centrifuge run. Operating
the centrifuge without these parts in
place could allow small particles to
exit the rotor chamber in the event of
a rotor failure.
C A U T I O N
!
Be sure the rotor is properly balanced and seated on the drive
spindle. All four buckets must be
used on every run (even if empty).
See rotor instruction manual.
To perform the run:
1. Set the POWER switch to "I".
2. Press the DOOR switch to release the chamber door.
3. Install the rotor on the drive spindle and close the chamber
door. When properly closed, the lid latch automatically locks
the door and the READY indicator light comes on.
4. Set the SPEED dial to the desired run speed.
NOTE
5. Turn the TIME dial to the desired run time (the run time, in
Selected run speed is to be verified and adjusted during
the run after the value shown in the SPEED display has
stabilized. Adjust the SPEED dial until the SPEED
display indicates desired run speed (in rpm). If it is not
disturbed, the SPEED dial will retain its position, allowing
for run-to-run repeatability.
minutes, will appear in the TIME display); or press the HOLD
switch to ON for a continuous run and two dashes (--) will
appear in the TIME display.
6. Press START switch to begin run.
NOTE
7. At the end of the run, the DOOR indicator light blinks indicating
NOTE
If the door is not properly closed, the READY indicator
light will not come on and the rotor will not spin when the
START switch is pressed.
To end a run before the selected run time has elapsed or
to end a run set to HOLD, press the STOP switch.
that the chamber door can be opened. Press the DOOR switch to
open the chamber door.
Remove the sample from the rotor, close the chamber door, and
set the POWER switch to "O".
The speed and time values selected at the beginning of
the run are automatically retained unless the power cord
is disconnected from the power source. To do another
run with the same run speed and time parameters:
prepare the rotor, install it in the centrifuge, close the
chamber door, and press the START switch.
2-6
TC6
®
Installation and Operation
2-9. Emergency Sample
Recovery
If the main power shuts off because of a power failure or system
malfunction, the chamber door will not open. A mechanical override is provided to allow sample recovery in the case of an emergency.
W A R N I N G
!
This procedure is included
for
emergency sample recovery only
and should never be used for any
purpose other than those explained
in this section.
When the main power shuts off, the
brake will not operate. Unplug the
centrifuge plower cord and wait until
the motor stops spinning
ing the mechanical override.
before
us-
The mechanical override is located below the air inlet vent in the
front panel, as shown in figure 2-3. To operate the override, insert
the end of the override key (PN 78170 supplied), at a slight upward
angle 2/3 of the way into the hole. Carefully move the key left-toright until you locate the solenoid shaft. Slowly move the end of the
key downward to contact the washer located at the bottom of the
shaft. With the key pressed tight against the solenoid shaft, use the
key as a lever to apply downward pressure on the washer to release
the chamber door.
Figure 2-2. Location of the Mechanical Override
2-7/2-8
2-7
®
SORVALL Centrifuges
INSTALLATION CHECKLIST
TC6® TABLETOP
CENTRIFUGE
Institution _________________________________
Street Address _____________________________
___________________________________________
City _______________________________________
State/Province _____________________________
Postal Code ________________________________
Country ___________________________________
Phone No. _________________________________
Inspection (paragraph 2-1)
Shipping damage
Accessories included
Preinstallation (paragraph 2-2)
Confirm voltage on instrument
Electrical Requirements
(paragraph 2-3)
Line voltage
Ground Continuity
Date _________________________________
Serial Number _______________________
Packing List No.______________________
User _________________________________
Installed by __________________________
Voltage Selection (paragraph 2-4)
Check fuse block/correct fuses
Installation (paragraph 2-5)
Sturdy bench
Level surface
Operation (paragraph 2-8)
Perform run
Acceleration time
Deceleration time
Door Latch
Comments: ______________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
Signature of Installer ____________________________________________________________________
Date
®
TC6
Contents
Section 3. System Descriptions
3-1. General System Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
3-2. Power System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2
3-3. Drive Motor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2
3-4. Brushless Motor Drive Electronics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2
3-5. Speed Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6
3-6. Timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7
3-7. Door Latching Mechanism. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7
Table of Contents
Page
ix
®
TC6
Section 3: SYSTEM DESCRIPTIONS
3-1. General System Description
The TC6® is an assembly that consists of the following:
• Power System
• Drive Motor System
• Control System
• Input/Output System
• Cabinet System
• Ventilation System
• Containment System
The Power System consists of the cord, voltage selector (SN 9501733
and below), power supply, and electrical connectors. It takes electricity from the electric outlet, converts it to low voltage and then
distributes it to the other instrument systems.
System Descriptions
The Drive Motor System consists of the motor, drive electronics and
drive mount hardware. It receives controlled voltage from the control
system to spin the rotor while providing support for itself and the
rotor system.
The Control System consists of electrical circuits that are located on
printed circuit boards to control operation of the motor speed, the
timer and the latch mechanism.
The Input/Output System is a user interface system that consists of
knobs, switches, and displays. It allows the user to input run
parameters and also monitors a run in progress.
The Cabinet System consists of the upper and lower frame sections.
This system forms the main body of the centrifuge and supports the
other instrument systems.
The Ventilation System consists of a fan, gaskets and baffles. It
directs air movement in the centrifuge to cool the circuits and motor
and also seals the rotor chamber to minimize windage.
The Containment System consists of radial and vertical containment
sub-systems. The radial sub-system is the guard and containment
rings and their supports. The vertical containment sub-system is
the door, latch and striker, and the mounting hardware. The
containment system is designed to contain any parts or fragments
that may result from a rotor failure.
3-1
System Descriptions
SORVALL Centrifuges
3-2. Power System
Theory of Operation
The electrical power portion of this centrifuge starts in the line cord
entry module. This module accepts a standard three wire power
cord. Both sides of the line are fused. The 100 - 120 volt centrifuges
are fused at 3.15 amps and the 220 - 240 volt centrifuges at 2 amp.
(SN 9501733 and below), 120 V (±10%) and 230 V (±10%) (SN
9501734 and above). This centrifuge is designed to work on either
50 or 60 hertz at any of the input voltages. No changes are necessary
to accommodate different line frequencies.
The other portion of the power system is the dc power supply. This
is a dual supply generating nominally 30␣volts at 10␣amps and
5␣volts at 500␣milliamps. Ther e is a fast acting fuse of 6.3␣amps on
the 30␣volt secondary of the transformer and a fast-acting fuse of 1.6
amps on the 5␣volt secondary of the transformer . The bridge rectifiers and 5 volt regulator are heatsinked to the chassis. The 30␣volt
supply is used by the motor control circuitry, the motor, and the
latch release solenoid. The 5␣volt supply is for powering the displays, speed and timer logic; and the operator I/O logic.
3-3. Drive Motor
Theory of Operation
The motor is a brushless dc type. Four Ferrite magnets are adhesive
bonded to the steel shaft to make up the rotor. Arranged around the
rotor in the case are three excitation coils. To sense motor position,
three␣Hall-ef fect devices are mounted at the bottom of the case.
3-4. Brushless Motor Drive
Electronics
The TC6® drive is a type of power inverter motor drive. The functional purpose is to convert raw single phase ac power into synchronous three-phase power to the motor. This is accomplished in
several stages. The following is a brief description of how the
internal power conversion process occurs.
Power Conversion from ac to dc – The ac power source may be
selected for a nominal voltage of 100 - 120 or 220 - 240 volts ac-RMS
at a frequency of between 48 to 62 Hz. Only single phase ac is used.
Raw ac, used for the motor power, passes into a full wave bridge
3-2
TC6
®
System Descriptions
rectifier and then into filter capacitors. The combination of these
components provides a nominal 30 volt unregulated dc power
source.
Power Inversion from dc to ac – The unregulated dc power available
in the TC6® must be converted back to phased ac power for the
motor to operate. This process is called inversion. For proper control
of motor rotation, the drive must synchronize the application of
power precisely with the rotational position of the rotor. This process
is commonly referred to as commutation. The motor used in the
centrifuge requires three-phase ac power for commutation.
The three-phase ac power used to "commutate" the motor is phase
displaced in time by 120 electrical degrees. The ac power delivered
is pulsed square waves and provides variable frequency ac to the
motor. This feature enables the motor to operate at variable speeds.
The three-phase ac power delivered to the motor is developed by an
active circuit network consisting of six power transistors. This network is called the output bridge. In order to sustain the rotation of
the centrifuge the drive continuously processes and decodes rotor
position information. This information is used to sequentially apply
power from the output bridge to the motor.
It is not sufficient to precisely control the motor through commutation
alone. The power applied to the motor must be carefully metered in
order to throttle both torque and speed. This is accomplished through
a technique called pulse width modulation, or PWM.
The PWM technique provides a method of efficient power control
through the use of high frequency output bridge modulation. In
effect, as each motor winding is turned on in sequence during
motor rotation, PWM is superimposed upon the normal
commutation signals. PWM results in the application of power to
the motor by chopping it on and off at a high rate (24 kHz). This
chopping scheme controls average motor current by varying the
ratio of "on time" versus "off time" for each PWM cycle. This chopping
scheme provides proportional output torque from the motor through
the direct adjustment of the average motor current.
The drive limits torque by continuously monitoring the electrical
current to the motor and comparing it to the commanded level
requested by the control setting. The difference between these two
levels results in an error signal which is then converted to a PWM
ratio. This PWM is used to modulate the output bridge as described
above.
3-3
System Descriptions
SORVALL Centrifuges
a. Theory of Operation
The drive is built with Motorola's MC33035 and a support chip
MC33039.
The MC33035 is a 24-pin linear integrated circuit (I.C.) that operates
as the control center for the brushless dc motor control system. The
main functions of MC33035 are to decode the signals from the
Hall-effect sensors and generate logic for electronically commutating
the motor. The commutation logic is internally delivered to the six
output drivers consisting of three open collector NPN transistors
that drive the upper legs of the bridge and three totem pole drivers
that control the devices. The open collector outputs can sink 50 mA.
With some additional circuitry this allows control of either N-channel
MOSFETs for higher power applications or P-channel MOSFETs if a
simple interface is desired. Since the three lower totem pole outputs
can source and sink 10 mA, they can drive power MOSFETs directly.
b. Fault Management
The MC33035 can detect and manage several types of faults. A
common method of overcurrent detection is to tie the sources of the
lower three transistors together and return them to the negative
supply rail through a current sense resistor. The sense voltage,
which is proportional to load current, is delivered into a comparator
on board the MC33035. The comparator then delivers an RS flip-flop,
which ensures that the output drivers will turn off the power
transistors for the remainder of the oscillator cycle if an overcurrent
condition is detected. Without the internal flip-flop, the overcurrent
protection loop would rapidly cycle on and off about the
comparator's threshold, causing excessive power transistor heating.
In addition to overcurrent management, the MC33035 provides
undervoltage lockouts that terminate the drive to the output transistors if any of three conditions occur:
• insufficient voltage to operate the I.C.;
• insufficient voltage to drive the power MOSFET gates; or
• output drivers turn the power transistors off when the MC33035
does not sustain its on-board 6.25 V reference.
An invalid set of Hall-effect signals or excessive temperature will
also cause shutdown.
3-4
Whenever any fault condition exists, an NPN transistor capable of
sinking 16 mA pulls the Fault Output pin low.
TC6
®
System Descriptions
c. Control Features
The MC33035's circuitry contains all except one major element for
closed-loop speed control. The missing element is that which
monitors motor rpm (speed) and generates a signal proportional to
motor speed, a function that has been the domain of a tachometer
Once provided with a motor speed signal, the MC33035's high
performance error amplifier and its internal oscillator form the last
major links in the speed control loop.
The MC33035's on-board oscillator operates at a frequency set by an
external resistance/capacitance (R-C). Each cycle capacitor is charged
from the reference output through a resistor and then rapidly
discharged through an internal transistor.
At each positive or negative transition of the Hall-effect sensors,
the MC33039 generates a pulse with a fixed on time. The output
signal can then be filtered to obtain a voltage proportional to motor
speed. Design of an MC33035/39 based system should begin with
setting the system timing, which originates in the MC33039. Selection
of timing components for MC33039 is based on the desired maximum
motor rpm. For the motor used in this application, there are two
electrical degrees for every mechanical degree since the permanent
magnet on the rotor has two pairs of poles. Therefore, for every
mechanical revolution each Hall-effect sensor delivers two pulses
and the three sensors generate six pulses. The MC33039 generates
12 pulses for each revolution, one for each rising and falling edge.
For a given maximum rotor speed, the output pulse width has a
maximum limit. For example, the maximum speed is 6000␣rpm,
which is 100␣r evolutions per second, the MC33039 will generate
100␣x␣12, or 1200␣pulses per second. The >1kHz␣fr equency determines that the maximum pulse width must be less than 1␣ms. One
can determine that R1 and C1 values of 30␣k and 22␣nF r esults in a
pulse width of 600␣ µs. To set the system PWM frequency, refer to the
MC33035's data sheet. There it shows that setting R2 and Cw to
5.1␣k and 0.01␣ µ F gives a nominal PWM frequency of 24␣kHz, just
above the audible range.
Both inputs and the outputs of the MC33035's error amplifier are
accessible to accommodate various control methods. For open-loop
control a reference signal proportional to the desired speed can be
fed into the error amplifier's non-inverting input. The error amplifier output is then configured as a unity gain voltage follower by
connecting its inverting input to its output. The error amplifier's
output is then compared to the output of the oscillator to obtain a
PWM signal proportional to the desired motor speed--unless the
control loop is overridden by an overcurrent or fault condition.
3-5
System Descriptions
SORVALL Centrifuges
For closed-loop control, one approach is to filter the MC33039's
output with a low pass filter to generate a voltage proportional to
motor speed and feed the resulting signal into the inverting input of
the MC33035's comparator. A signal proportional to desired motor
speed drives the non-inverting input, and the ratio of the input and
feedback resistors R3 and R4 control gain. In this design, low pass
filtering and generating the error signal are combined by using
feedback capacitor, C3.
Ideally, the integrator/error amplifier should produce a ripple free
output even at low motor speeds. To do so at very low speeds
reduces system response time, however. Component values must
be adjusted according to the rotors' load, inertia and friction. In this
particular application the values 2 M ohm and 0.01 µF give good
dynamic response and stability.
When motor speed is less than the desired speed, the MC33035
extends the output pulse width to the drive transistors. When
motor speed is greater than the desired speed, the duty cycle decreases. However, if the input signal abruptly demands a much
lower speed, the duty cycle could fall to zero and the motor would
coast to desired low speed. Therefore, since the MC33035 has no
provision to dynamically brake the motor and thus control rapid
deceleration, it is best suited for applications which have a large
frictional load or those that do not require a controlled, abrupt
deceleration.
d. Braking
Dynamic braking is used. The three high-side motor drive transistors are turned off and the three low-side drive transistors are
turned on, in sequence. This circulates the back Electro Magnetic
Force (EMF) generated currents through the motor winding for
dissipation of stored energy.
A logic high at pin 2 of the motor drive control connector calls for
dynamic braking.
3-5. Speed Control
Theory of Operation
Speed control is accomplished by a 10k ohm potentiometer used in
conjunction with the Motorola brushless motor control chip
integrated circuit set (MC33035 and MC33039). The wiper of the
potentiometer is the control input to MC33035. Lower speed is
selected when the voltage on the wiper is decreased (by turning
counterclockwise) and higher speed is selected when voltage on the
wiper is increased (by turning clockwise).
3-6
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