THOMSON TS 870 User manual

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TS 870
AUTOMATIC TRANSFER SWITCHES
INSTALLATION, OPERATING &
SERVICE MANUAL
PM062 Rev 6 08/08/01

TS 870 TRANSFER SWITCH
PM062 REV 6 08/08/01 Thomson Technology
TABLE OF CONTENTS
1. PRODUCT REVISION HISTORY 1
2. EQUIPMENT STORAGE 1
2.1. ENVIRONMENTAL CONDITIONS 1
3. NOTES TO INSTALLER 2
3.1. UPSTREAM CIRCUIT PROTECTIVE DEVICES/ELECTRICAL CONNECTIONS 2
3.2. TRANSFER SWITCHES WITH INTEGRAL OVER CURRENT PROTECTION 3
3.3. TRANSFER SWITCHES WITH MULTI-TAP VOLTAGE CAPABILITY 3
3.4. SYSTEM PHASING-HIGH LEG DELTA SYSTEMS 4
3.5. REMOTE START CONTACT FIELD WIRING 5
3.6. DIELECTRIC TESTING 5
3.7. INSTALLATION OF OPEN TYPE TRANSFER SWITCHES 5
4. GENERAL DESCRIPTION 5
4.1. PRODUCT MODEL CODE 7
4.2. TYPICAL COMMISSIONING PROCEDURES 8
5. GENERAL THEORY OF OPERATION 8
5.1. STANDARD AUTOMATIC TRANSFER SWITCH 8
5.2. SERVICE ENTRANCE AUTOMATIC TRANSFER SWITCH 9
5.3. TEST MODES 13
6. OVER CURRENT PROTECTION 13
6.1. STANDARD TS 870 AUTOMATIC TRANSFER SWITCH 13
6.2. OPTIONAL TS 870 AUTOMATIC TRANSFER SWITCH WITH INTEGRAL OVER
CURRENT PROTECTION 14
7. GENERAL NOTES ON SERVICING TRANSFER SWITCH MECHANISM 15
8. TRANSFER SWITCH MECHANISM – 100A-800A, S STYLE 17
8.1. MANUAL OPERATION 17

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PM062 REV 6 08/08/01 Thomson Technology
9. TRANSFER SWITCH MECHANISM –1000A-1200A, T-STYLE 19
9.1. MANUAL OPERATION 19
10. RECOMMENDED MAINTENANCE 21
11. FRONT VIEW (TYPICAL) 3 / 4 POLE 100A-250A S-STYLE TRANSFER
MECHANISM 23
12. FRONT VIEW (TYPICAL) 3 POLE 400A-800A S-STYLE TRANSFER MECHANISM
(MECHANISM FRONT COVER REMOVED) 24
13. FRONT VIEW (TYPICAL) 3 / 4 POLE 1000A-1200A T-STYLE TRANSFER
MECHANISM 25
14. CONNECTION CONFIGURATION OPTIONS 26
15. CABLE TERMINAL INFORMATION 27
16. REQUIREMENTS FOR UPSTREAM CIRCUIT PROTECTIVE DEVICES 27
16.1. WITHSTAND CURRENT RATINGS (ALL MODELS WITHOUT INTEGRAL
OVERCURRENT PROTECTION OPTION) 27
16.2. INTERRUPTING CAPACITY CURRENT RATINGS (ALL MODELS WITH INTEGRAL
OVERCURRENT PROTECTION OPTION) 28
17. GROUND FAULT SITE TEST REQUIREMENTS 28
17.1. PERFORMANCE TEST 28
18. TROUBLESHOOTING 30
19. REPLACEMENT PARTS 32
20. PRODUCT RETURN POLICY 33
21. NOTES 34
22. PERFORMANCE TEST FORM 35

TS 870 TRANSFER SWITCH
PM062 REV 6 08/08/01 1 Thomson Technology
1. PRODUCT REVISION HISTORY
The following information provides an historical summary of changes made to this product since the
original release.
Operating & Service Manual Version
Rev 0 04/11/19 Original release.
Rev 1 05/03/08 Changes to incorporate reversing style ATS Motor for 100-250A
transfer switches.
Rev 2 05/05/26 Revisions to Section 8 and Section 18.
Rev 3 06/05/08 Revisions to Section 15.
Rev 4 07/07/31 Changes to Incorporate new S-Style 400A mechanism
Rev 5 08/03/05 Changes to Incorporate new S-Style mechanism (100A, 150A,
200A, 250A, 600A, 800A)
Rev 6 08/08/01 Changes to Incorporate optional TSC 80E Transfer Controller
Contact Thomson Technology, to obtain applicable instruction manuals or if in doubt about
any matter relating to installation, operation or maintenance. Soft copy of the most current
version is available at www.thomsontechnology.com.
NOTE: All information contained in this manual is for reference only and is subject
to change without notice.
2. EQUIPMENT STORAGE
The following procedures are required for correct storage of the transfer switch prior to installation.
2.1. ENVIRONMENTAL CONDITIONS
CAUTION!!!
Failure to store and operate equipment under the specified environmental conditions may
cause equipment damage and void warranty.
2.1.1. EQUIPMENT STORAGE
The transfer switch shall be stored in an environment with a temperature range not
exceeding -4° to +158° Fahrenheit (-20° to +70° Celsius) and a humidity range not
exceeding 5%-95% non-condensing. Before storing, unpack sufficiently to check for
concealed damage. If concealed damage is found, notify the ATS supplier and the
Carrier immediately. Repack with the original, or equivalent packing materials.

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PM062 REV 6 08/08/01 2 Thomson Technology
Protect from physical damage. Do not stack. Store indoors in a clean, dry, well
ventilated area free of corrosive agents including fumes, salt and concrete/cement
dust. Apply heat as necessary to prevent condensation.
2.1.2. EQUIPMENT OPERATING
The transfer switch shall be operated in an environment with a temperature range not
exceeding +5° to +122° Fahrenheit (-15° to +50° Celsius) and a humidity range not
exceeding 5%-95% non-condensing.
3. NOTES TO INSTALLER
DANGER!!!!
Arc Flash and Shock Hazard. Will cause severe injury or death.
Do not open equipment until ALL power sources are disconnected
This equipment must be installed and serviced only by qualified electrical
personnel utilizing safe work practices and appropriate Personal Protective
Equipment (PPE). Failure to do so may cause personal injury or death
3.1. UPSTREAM CIRCUIT PROTECTIVE DEVICES/ELECTRICAL
CONNECTIONS
To ensure satisfactory installation of this equipment be sure to observe "Cable Terminal
Information” regarding power cable connection tightness and "Requirements for Upstream
Circuit Protective Devices" located in this manual.
All mechanical and electrical connections must be checked for tightness prior to placing this
equipment in service to ensure proper operation and to validate applicable warranty
coverage.

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PM062 REV 6 08/08/01 3 Thomson Technology
3.2. TRANSFER SWITCHES WITH INTEGRAL OVER CURRENT PROTECTION
For models of transfer switch with integral over current protection, the over current protection
must be set prior to operation. The equipment will be shipped from the factory with a long-
time current setting of 100% (of the equipment rating) and maximum short-
time/instantaneous current and time delay settings.
WARNING!
Do Not Energize this equipment until
device settings have been verified to
ensure proper system protection &
coordination. Failure to do so may
result in equipment failure.
Refer to Section 5.2.2 of this manual for additional information on operation of the Transfer
switch following an over current trip condition.
Refer to information supplied with the transfer switch documentation package for adjustment
procedures on the power switching units over current protection trip unit. Contact the factory
if any additional information is required.
3.3. TRANSFER SWITCHES WITH MULTI-TAP VOLTAGE CAPABILITY
If the transfer switch has programmable multi-tap voltage capability (i.e. ATS Model Code
with Voltage Code “Y”), confirm the transfer switch has been configured for the correct
system voltage prior to installation.
WARNING!
Failure to confirm and match transfer
switch voltage with the system voltage
could cause serious equipment damage.
The voltage selections and connections are shown on the engineered drawings attached to
each transfer switch. The factory default settings will be indicated on the calibration label
attached on the inside of the enclosure door (supplied loose on open style models). A blank
label is included to record the applicable settings if the configuration is changed from the
factory default settings.

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To change the transfer switch voltage, refer to “INSTRUCTIONS TO CHANGE SYSTEM
VOLTAGE ON TS870 SERIES TRANSFER SWITCHES WITH TSC 80/TSC 80E
CONTROLLER” (attached as “Appendix B). Contact Thomson Technology for further
information as may be required.
3.4. SYSTEM PHASING-HIGH LEG DELTA SYSTEMS
For systems using high leg delta 240V 3 phase 4 wire systems, connection of supply
conductors must have the correct phasing as shown below.
WARNING
Failure to match correct system
phasing will result in serious damage
to the TSC 80/TSC 80E controller.
208V
B
(O range)
(High Leg)
C
(Yellow)
A
(R ed)
N
(W hite)
PH A
(UA)
Autom atic Transfer
Switch (Utility Supply)
PH B
(UB)
PH C
(UC)
Neural
(N)
120V 120V
240V 240V
Where transfer switches are supplied without power isolation transformers (PT1 &
PT2) for ATS control logic it is essential that the orientation of phase conductors of

TS 870 TRANSFER SWITCH
PM062 REV 6 08/08/01 5 Thomson Technology
the supply source be arranged such that the phase of highest potential with respect
to ground is not connected to the power supply inputs to the controller (A Phase for
both supplies). Failure to do so will result in equipment damage.
Per NEC Article 384-3 (f) “The B phase shall be that phase having the higher voltage
to ground on a 3-phase, 4-wire delta connected systems.”
3.5. REMOTE START CONTACT FIELD WIRING
As a minimum, the remote engine start control field wiring shall conform to the local
regulatory authority on electrical installations. Field wiring of a remote start contact
from a transfer switch to a control panel should conform to the following guidelines to
avoid possible controller malfunction and/or damage.
3.5.1. Minimum #14 AWG (2.5mm2) wire size shall be used for distances up to 100ft
(30m)1). For distances exceeding 100 ft. (30m) consult Thomson Technology
3.5.2. Remote start contact wires should be run in a separate conduit.
3.5.3. Avoid wiring near AC power cables to prevent pick-up of induced voltages.
3.5.4. An interposing relay may be required if field-wiring distance is excessively
long (i.e. greater than 100 feet (30m)) and/or if a remote contact has a
resistance of greater than 5.0 ohms.
3.5.5. The remote start contact must be voltage free (i.e. dry contact). The use of a
“powered” contact will damage the transfer controller.
3.6. DIELECTRIC TESTING
Do not perform any high voltage dielectric testing on the transfer switch with the TSC
80/TSC 80E controller connected into the circuit as serious damage will occur to the
controller. All AC control fuses and control circuit isolation plugs connected to the
TSC 80/TSC 80E must be removed if high voltage dielectric testing is performed on
the transfer switch.
3.7. INSTALLATION OF OPEN TYPE TRANSFER SWITCHES
Please refer to the factory for additional information.
4. GENERAL DESCRIPTION
Thomson Technology TS 870 series of Automatic Transfer Switches employ two mechanically
interlocked enclosed contact power switching units and a microprocessor based controller to
automatically transfer system load to a generator supply in the event of a utility supply failure.

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System load is then automatically re-transferred back to the utility supply following restoration of the
utility power source to within normal operating limits.
The standard TS 870 series Automatic Transfer Switch is rated for 100% system load and requires
upstream over current protection. The TS 870 Automatic Transfer Switch may be supplied with
optional integral over current protection within the enclosed contact power switching units for
applications such as Service Entrance Rated equipment. Refer to Section 6 of this manual for
detailed information on over current protection.
The TS 870 series transfer switches use a type TSC 80 standard or optional TSC 80E
microprocessor based controller, which provides all necessary control functions for fully automatic
operation. The TSC 80/TSC 80E controller is mounted on the door of the transfer switch enclosure
and operating status is shown via LED lights. For further information on the TSC 80/TSC 80E
Transfer Controller, refer to separate instruction manual PM063.
The power switching devices used for the Utility and Generator sources are operated by an
electrically driven motor mechanism in the transfer switch. The transfer switch motor utilizes the
power from the source to which the electrical load is being transferred. The mechanism provides a
positive mechanical interlock to prevent both power switching units from being closed at the same
time, which allows an open transition, “break-before-make” transfer sequence. The TSC 80/TSC
80E transfer controller provides a standard neutral position delay timer to allow adequate voltage
decay during transfer operation to prevent out of phase transfers.
Note: For the purpose of this manual, the following standard nomenclature is utilized:
• Utility: to indicate the source of primary power
• Generator: to indicate the source of standby power
• Power switching device: to indicate the transfer switch power switching device

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4.1. PRODUCT MODEL CODE
The type of TS 870 series transfer switch supplied is identified by way of a 21 digit product
code which appears on the equipment rating plate (MODEL) on the door of the transfer
switch, and on the transfer switch drawings. The model code structure and definitions are as
follows:
1 2 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
T S 8 7
1-3. SERIES 15 . VOLTAGE 18. UTILITY SWITCHING DEVICE
TS - TRANSFER SWITCH 1
f
f f
f
3 WIRE K - MOLDED CASE SWITCH (100 - 1200 A)
D - 120/240 M - MOLDED CASE SWITCH C/W THER-MAG
4 & 5. MODEL 3
f
f f
f
4 WIRE (GROUNDED NEUTRAL) TRIP (100-200A)
87 - 870 SWITCH E - 120/208
1
N - MOLDED CASE SWITCH C/W ELECTRONIC
F - 127/220 TRIP (250-1200A)
6. POLES G - 120240
1
(DELTA) P - MOLDED CASE SWITCH C/W ELECTRONIC
2 - 2 POLE H - 220/380
2
& GF TRIP (250-1200A)
3 - 3 POLE J - 240/416
4 - 4 POLE K - 254/440 19. GENERATOR SWITCHING DEVICE
M - 277/480
1
K - MOLDED CASE SWITCH (100 - 1200 A)
7. CONFIGURATION TYPE N - 347/600
1
M - MOLDED CASE SWITCH C/W THER-MAG
A - ATS 3f
f f
f 3 WIRE TRIP (100-200A)
X - SPECIAL P - 208
N - MOLDED CASE SWITCH C/W ELECTRONIC
Q - 220 TRIP (250-1200A)
8 - 11. AMPERAGE R - 240 P - MOLDED CASE SWITCH C/W ELECTRONIC
0100 S - 380
2
& GF TRIP (250-1200A)
0150 U - 416
0200 V - 480 20. POWER CONNECTIONS
0250 W - 600 A - STANDARD
0400 X - SPECIAL X - SPECIAL
0600
0800 16. CONTROLLER 21. ATS CONNECTION CONFIGURATION
1000 1 - TSC80 A - STANDARD
1200 3 - TSC 80e B - ALTERNATE B (1000-1200A)
7 - NONE (MANUAL) C - ALTERNATE C (1000-1200A)
12. APPLICATION
17. ENCLOSURE TYPE
D - ALTERNATE D (1000-1200A)
A - STANDARD
B - SERVICE ENTRANCE A - NEMA1, ASA #61 GREY REFER TO DRAWING #870M100
X - SPECIAL B - NEMA2, ASA #61 GREY
C - NEMA12, ASA #61 GREY
13. OPERATION TYPE D - NEMA3R SD, ASA #61 GREY
1 - OPEN TRANSITION E - NEMA3R/4 DD, ASA #61 GREY
3
NOTES
2 - MANUAL ELEC. OP. F - NEMA3RX/4X DD
1
MULTI-VOLTAGE CAPABLE
X - SPECIAL (306 STAINLESS STEEL)
3
2
FOR 50 Hz APPLICATION
G - NONE (OPEN STYLE)
3
STANDARD ENCLOSURE RATING IS N3R
14 . SAFETY STANDARDS H - NEMA 3RXDD (ALUMINUM) AT 800A AND ABOVE AND N4 AT 600A
A - UL 1008 ASA #61 GREY
4
AND BELOW
B - CSA C22.2 NO 178 X - SPECIAL
4
ONLY AVAILABLE 800A AND ABOVE
X - NOT APPLICABLE

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PM062 REV 6 08/08/01 8 Thomson Technology
4.2. TYPICAL COMMISSIONING PROCEDURES
CAUTION:
Commissioning procedures must be performed by qualified
personnel only. Ensure the Automatic Transfer Switch
(ATS) Control Circuit Isolation Plug is disconnected prior to
energizing the supply sources. Manually place the transfer
switch mechanism in the neutral position prior to applying
power. Failure to do so may result in equipment failure or
personal injury.
Note: The TYPICAL AUTOMATIC TRANSFER SWITCH COMMISSIONING
PROCEDURES MODEL SERIES TS 870 (attached as “Appendix A ”) is provided for
general information only pertaining to typical site installations and applications. Contact
Thomson Technology for further information as may be required.
Note: An optional hand held, plug-in Service Display Module (SDM) is available for the TSC
80 Transfer Controller. The SDM module provides an LCD screen to display additional
detailed information on the operation and settings of the TSC 80 controller for simplified
servicing/trouble shooting procedures. For detailed information, refer to the separate SDM
module instruction manual (PM065). TSC 80e transfer controllers have a built-in LCD display
and therefore do not require the SDM unit.
5. GENERAL THEORY OF OPERATION
5.1. STANDARD AUTOMATIC TRANSFER SWITCH
5.1.1. NORMAL OPERATION
When utility supply voltage drops below a preset nominal value (adjustable from 70%
to 100% of nominal) on any phase, an engine start delay circuit is initiated and the
transfer to utility supply signal will be removed (i.e. contact opening). Following
expiry of the engine start delay period (adjustable from 0 to 60 sec.) an engine start
signal (contact closure) will be given.
Once the engine starts, the transfer switch controller will monitor the generator
voltage and frequency levels. Once the generator voltage and frequency rises above

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PM062 REV 6 08/08/01 9 Thomson Technology
preset values (adjustable from 70% to 95% of nominal), the engine warm-up timer
will be initiated. Once the warm-up timer expires (adjustable from 0 to 60 sec.), the
Transfer to Generator Supply signal (contact closure) will be given to the transfer
switch mechanism. The load will then transfer from the utility supply to the generator
supply via the motor driven mechanism.
The generator will continue to supply the load until the utility supply has returned.
The retransfer sequence is completed as follows: when the utility supply voltage is
restored to above the preset values (adjustable from 70% to 95% of nominal) on all
phases, a transfer return delay circuit will be initiated. Following expiry of the Utility
Return Timer (adjustable from 0 to 30 min.), the Transfer to Generator Supply signal
will be removed (contact opening), then the Transfer to Utility Supply signal (contact
closure) will be given to the transfer switch mechanism. The load will then retransfer
the load from the generator supply back to the utility supply. Note: A neutral delay
timer circuit will delay the transfer sequence in the neutral position (i.e. both power
switching devices open) until the neutral delay time period expires (adjustable from 0
to 60 seconds).
An engine cooldown timer circuit will be initiated once the load is transferred from the
generator supply. Following expiry of the cooldown delay period (adjustable from 0
to 30 minutes), the engine start signal will be removed (contact opening) to initiate
stopping of the generator set.
5.2. SERVICE ENTRANCE AUTOMATIC TRANSFER SWITCH
Note: This applies only to service entrance transfer switches
5.2.1. NORMAL OPERATION
Under normal conditions, the load is energized from the utility supply through the
closed utility transfer power switching device. If the utility power fails, the generator
will start and the load will be re-energized via the closed generator transfer power
switching device.
In the normal operating mode, the Service Disconnect switch shall be in the
“energized” position.
5.2.2. OVER CURRENT TRIP
Should the utility power switching device trip open due to an over current condition,
TSC 80/TSC 80E transfer controller will initiate an engine start signal and will permit

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PM062 REV 6 08/08/01 10 Thomson Technology
transfer of the load to the generator supply. The utility source will be locked out and
the load will remain on the generator supply until the TSC 80/TSC 80E alarm signal is
manually reset.
Refer to the TSC 80/TSC 80E Instruction Manual for further details on Transfer Fail
operation.
Should the generator power switching device trip open due to an over current
condition, TSC 80/TSC 80E transfer controller will initiate transfer of the load to the
utility supply. The generator source will be locked out and the load will remain on the
utility supply until the TSC 80/TSC 80E alarm signal is manually reset.
5.2.3. SERVICE DISCONNECT PROCEDURE
To perform a service disconnect (i.e. to disconnect the utility and generator supplies),
the following procedure is required:
1. Move the "Service Disconnect" control switch located on the door of the
transfer switch to the "Disconnected" position.
2. Verify that the "Service Disconnected" pilot light is illuminated. If the Light
is illuminated, the service has been successfully disconnected and it is safe to
perform any maintenance procedures as required. In this condition, the
transfer switch is in the neutral position, with both utility and generator transfer
power switching devices open. The transfer switch will remain in this
condition, regardless of condition of the utility and generator supplies (i.e. if
the utility power fails, the generator will not receive a start signal, nor will the
transfer switch move to the generator position). NOTE: If the Service
Disconnect Light is not illuminated, additional procedures are required (refer
to the following procedure #5.2.4).
3. Attach safety lockout padlock to the "Service Disconnect" control switch to
prevent unauthorized change in operating condition and verify transfer switch
door is locked closed. If the door is not locked, turn and remove door key.
WARNING!
Close and lock the transfer switch enclosure door
before connecting power sources.

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4. To reenergize the load, remove the padlock(s) from the service disconnect
control switch, and move the switch to the energized position. The transfer
switch will immediately return to the utility or generator supply if within normal
operating limits.
5.2.4. ADDITIONAL PROCEDURES
If the "Service Disconnected" pilot light is not illuminated, the service will not
have been successfully disconnected and therefore it is not safe to perform
any maintenance until the following additional procedures are performed:
DANGER!!!!
Arc Flash and Shock Hazard. Will cause severe injury or death.
Do not open equipment until ALL power sources are disconnected
This equipment must be installed and serviced only by qualified electrical
personnel utilizing safe work practices and appropriate Personal Protective
Equipment (PPE). Failure to do so may cause personal injury or death
1. Open the door to the transfer switch using a suitable tool and opening the
door lock with the key.
2. Visually inspect the actual position of the transfer switch mechanism. If the
position of the transfer switch mechanism is clearly in the "neutral position"
and the load bus is de-energized on all phases, the service has been
successfully disconnected. Proceed to Step. 4.
If the position of the transfer switch mechanism is not in the neutral position or
the load bus is energized, further procedures are required.
Note: If the position of the transfer switch mechanism is clearly in the "neutral
position, the "service disconnected" pilot light may not have illuminated due to
the following reasons:
a) Utility and generator supply voltages are not present (the pilot light
requires AC supply voltage to be present).
b) The pilot light may be burnt out. The bulb should be immediately
replaced with a suitably rated bulb.

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c) Failure of one or more of the sensing/logic contacts. A qualified
service technician is required to trouble shoot this specific condition.
Switch the utility control circuit isolation switch to the de-energized position
to remove utility control power. To isolate the generator supply, remove
the control circuit isolation plug. Note: The AC power conductors will still
remain energized. Once all the control circuits are de-energized and
isolated the "Service Disconnected" pilot light will not illuminate due to loss
of control power.
Note: To return the transfer switch back to normal operation, the utility
control circuit disconnect switch and control circuit isolation plug must be
switched on and reconnected for correct operation.
3. If the position of the transfer switch mechanism is not in the "neutral
position", manually operate the transfer switch mechanism depending on
mechanism type as follows:
Note: Refer to product drawings in sections 12, 13 & 14 for identification of
Transfer Switch Mechanism style supplied with the Transfer Switch.
a. T-Style Mechanism: Pull the manual release plunger on
the mechanism, releasing the motor drive rod from motor
drive arm and move the knob and yoke to the marked
“neutral position”.
b. S-Style Mechanism: Insert the operating handle into the
front of the transfer mechanism and turn the operating
handle until the position indication on the mechanism
clearly shows the “neutral position”.
WARNING!
Failure to move the mechanism to the Neutral
Position may result in serious personal injury
or death due to electrical shock.
4. Close the transfer switch door securely using a suitable tool. Lock the door
in the closed position and remove the key.
WARNING!

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Failure to positively lock closed and secure the
transfer switch door may result in serious
personal injury or death due to electrical shock.
5. Attach a safety lockout padlock to the service disconnect control switch to
prevent unauthorized change in operating condition and verify transfer switch
door is locked closed.
6. To reenergize the load, remove the padlock(s) from the service
disconnect control switch, and move the switch to the Energized position.
The transfer switch will immediately return to the utility or generator supply if
within normal operating limits.
5.3. TEST MODES
The transfer switch may be tested utilizing the TSC 80/TSC 80E controller push-buttons or
optional four position test switch. A simulated utility power failure condition will be activated
when the test mode is selected. The transfer switch will operate as per a normal utility
power fail condition.
The transfer switch will remain on generator supply until the test mode is terminated. It will
then immediately transfer back to the utility supply and then continue to operate the
generator set for its cooldown period then stop. Note: The transfer switch will automatically
return to the utility supply (if within nominal limits) if the generator set fails while in the test
mode.
6. OVER CURRENT PROTECTION
Thomson Technology TS 870 series of Automatic Transfer Switches may be supplied with or
without integral over current protection as described below:
6.1. STANDARD TS 870 AUTOMATIC TRANSFER SWITCH
The standard TS 870 Automatic Transfer Switch does not contain any integral over current
protection and requires upstream over current protection devices for both Utility and
Generator sources. The Standard TS 870 is rated for 100% continuous loading and can
withstand a maximum short circuit fault current as noted in Section 15 of this manual. The
standard TS 870 transfer switch model without integral over current protection is identified in
the product model code. Refer to Section 4.1 of this manual for further details on model
coding.

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PM062 REV 6 08/08/01 14 Thomson Technology
6.2. OPTIONAL TS 870 AUTOMATIC TRANSFER SWITCH WITH INTEGRAL
OVER CURRENT PROTECTION
TS 870 transfer switches will have integral over current protection supplied on the Utility
source as standard. The type of over current protection utilized is dependent upon ATS
amperage size and optional features specified. For transfer switches rated 100A through
200A, over current protection is non-adjustable thermal-magnetic type trip units. For transfer
switches rated 400A through 1200A over current protection is adjustable electronic type with
long time & instantaneous trip unit elements with optional ground fault protection elements.
Note: Ground fault protection is supplied as standard on 1000A and 1200A transfer switches
that are used on systems greater than 240V.
An upstream over current protection device is required on the generator source which feeds
the TS 870 Transfer Switch if integral over current protection option is not specified on the
ATS.
Note: For models of transfer switch with adjustable integral over current protection trip units,
the over current protection must be set prior to operation. The equipment will be shipped
from the factory with a long-time current setting of 100% (of the equipment rating) and
maximum instantaneous/short-time current and time delay settings.
WARNING!
Do Not Energize this equipment until
device settings have been verified to
ensure proper system protection &
coordination. Failure to do so may result
in equipment failure.
Refer to Section 4.1 Product Model Code for types of integral over current protection which
are supplied with the transfer switch.

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PM062 REV 6 08/08/01 15 Thomson Technology
7. GENERAL NOTES ON SERVICING TRANSFER SWITCH
MECHANISM
DANGER!!!!
Arc Flash and Shock Hazard. Will cause severe injury or death.
Do not open equipment until ALL power sources are disconnected
This equipment must be installed and serviced only by qualified electrical
personnel utilizing safe work practices and appropriate Personal Protective
Equipment (PPE). Failure to do so may cause personal injury or death
Note: Refer to product drawings in sections 12, 13 & 14 for identification of Transfer Switch
Mechanism style supplied with the Transfer Switch.
When performing any service work on the transfer mechanism, it is imperative that the following be
observed:
7.1. To maintain mechanical integrity, ensure that:
• On T Style mechanisms, all limit switches are correctly adjusted to provide full
travel of the power switching device toggles without exerting unnecessary forces
associated with excessive travel. Ensure that power switching device travel far
enough to reset any internal trip unit (it is more important for the toggle to go fully
in the "off" direction, than in the "on" direction).
• Mechanical interlocking is correct when one power switching opens well before
the other should close.
• All fasteners are adequately tightened.
• The operating linkages are not damaged or bent, and that all bearing points
operate freely.
• On S style transfer switch mechanisms, check nylock nuts on bolt pivot points.
Operation arms should move freely without excessive play.
7.2. To maintain electrical integrity, ensure that:
• All electrical connections, especially power connections, are clean and
adequately tightened. Corroded or loose power connections will cause
destructive heating, and may cause premature tripping.
• All insulating devices are in place and in good condition.

TS 870 TRANSFER SWITCH
PM062 REV 6 08/08/01 16 Thomson Technology
• No moisture or other contamination is present.
• Electrical conductors are adequately secured away from moving parts.
7.3. To maintain operational integrity, ensure that:
• All control devices are in good condition and correctly calibrated.
• All control devices are adequately secured in their plug-in fixtures.
Only qualified personnel should undertake Service work. Failure to correctly maintain an
automatic transfer switch may present a hazard to life and equipment. Full operational
testing must be done prior to placing a transfer switch in service subsequent to any
maintenance or repair. Any service work involving electrical components requires high-
potential testing to ensure that required insulation levels have been maintained.