THOMSON TS 840 User manual

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TS 840
AUTOMATIC TRANSFER SWITCHES
INSTALLATION, OPERATING &
SERVICE MANUAL
PM057 Rev 8 10/01/25

TS 840 TRANSFER SWITCH
PM057 REV 8 10/01/25 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. SYSTEM PHASING-HIGH LEG DELTA SYSTEMS 4
3.4. REMOTE START CONTACT FIELD WIRING 5
3.5. DIELECTRIC TESTING 5
3.6. INSTALLATION OF OPEN TYPE TRANSFER SWITCHES 5
3.7. MOUNTING OF ENCLOSED TRANSFER SWITCHES 5
4. GENERAL DESCRIPTION 8
4.1. PRODUCT MODEL CODE 10
4.2. TYPICAL COMMISSIONING PROCEDURES 11
5. GENERAL THEORY OF OPERATION 11
5.1. STANDARD AUTOMATIC TRANSFER SWITCH 11
5.2. SERVICE ENTRANCE AUTOMATIC TRANSFER SWITCH 12
5.3. TEST MODES 16
6. OVER CURRENT PROTECTION 16
6.1. STANDARD TS 840 AUTOMATIC TRANSFER SWITCH 16
6.2. OPTIONAL TS 840 AUTOMATIC TRANSFER SWITCH WITH INTEGRAL OVER
CURRENT PROTECTION 16
7. GENERAL NOTES ON SERVICING TRANSFER SWITCH MECHANISM 18
8. TRANSFER SWITCH MECHANISM OPERATION–100A-800A, S STYLE20

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8.1. MANUAL OPERATION 20
9. RECOMMENDED MAINTENANCE 22
10. FRONT VIEW (TYPICAL) 3 POLE 100A-250A S-STYLE TRANSFER MECHANISM23
11. FRONT VIEW (TYPICAL) 3 POLE 400A-800A S-STYLE TRANSFER MECHANISM
(MECHANISM FRONT COVER REMOVED) 24
12. FRONT VIEW (TYPICAL) 3 POLE 400A-800A S-STYLE TRANSFER MECHANISM25
13. CABLE TERMINAL INFORMATION 26
14. REQUIREMENTS FOR UPSTREAM CIRCUIT PROTECTIVE DEVICES 26
14.1. WITHSTAND CURRENT RATINGS (ALL MODELS WITHOUT INTEGRAL
OVERCURRENT PROTECTION OPTION) 26
14.2. INTERRUPTING CAPACITY CURRENT RATINGS (ALL MODELS WITH INTEGRAL
OVERCURRENT PROTECTION OPTION) 27
15. GROUND FAULT SITE TEST REQUIREMENTS 27
15.1. PERFORMANCE TEST 27
16. TROUBLESHOOTING 29
17. REPLACEMENT PARTS 31
18. PRODUCT RETURN POLICY32
19. NOTES 33
20. PERFORMANCE TEST FORM34

TS 840 TRANSFER SWITCH
PM057 REV 8 10/01/25 1Thomson 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 02/06/17 Original release.
Rev 1 04/11/19 Change Controller From TSC 800 to TSC 80 Controller.
Rev 2 05/03/ 08 Changes to incorporate reversing style ATS Motor for 100-250A
transfer switches.
Rev 3 05/05/17 Revisions to Section 5 and Section 18.
Rev 4 06/05/08 Revisions to Section 15.
Rev 5 07/07/31 Changes to Incorporate new S Style 400A mechanism
Rev 6 08/01/07 Revisions to Appendix A
Rev 7 08/03/05 Changes to Incorporate new S Style mechanism (100A, 150A,
200A, 250A, 600A, 800A)
Rev 8 10/01/25Changes to Incorporate Seismic Certification and Mounting
Requirements
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.

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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.
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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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.

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3.3. 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 controller.
208V
B
(Orange)
(High Leg)
C
(Yellow)
A
(Red)
N
(White)
PH A
(UA)
Automatic 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

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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.”
3.4. 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.
3.5. DIELECTRIC TESTING
Do not perform any high voltage dielectric testing on the transfer switch with the TSC
80 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 must
be removed if high voltage dielectric testing is performed on the transfer switch.
3.6. INSTALLATION OF OPEN TYPE TRANSFER SWITCHES
Please refer to the factory for additional information.
3.7. MOUNTING OF ENCLOSED TRANSFER SWITCHES
Model TS840, TS870 and TS880 Automatic Transfer Switches and Automatic
Transfer and Bypass Isolation Switches in "standard" enclosures are seismic
certified under AC156 building code for non-structural components.

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"Standard" enclosures are all transfer switch enclosures Thomson Technology offers
in NEMA 1, NEMA 2, NEMA 3R and NEMA 4X for the above listed product. If a
customer requests a custom enclosure it would not be covered under the generic
certificate; if certification were a requirement Consult factory before ordering.
The Automatic Transfer Switches are qualified to the highest known level in North
America; based on site class D. Specifically this is a spectral acceleration of 342%.
The transfer switch must be installed per the anchoring details provided for seismic
qualification. The equipment can be mounted in alternate means and still qualify if a
qualified Civil Engineer designs the alternate method of anchoring.

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Anchoring Notes:
1. Anchoring must be designed according to IBC 2006 or latest version.

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2. The anchoring details shown are recommended according to the seismic
certification; design Engineer may use alternate anchors within the scope of IBC.
3. Wall anchors in concrete; use a typical concrete anchor as necessary.
4. Expansion anchors as shown to be installed according to manufacturer's
recommendation.
5. The 800-1200A NEMA 3R ATS enclosure may be floor/wall mounted or it may be
free standing (floor mounted only); If free standing it must be a minimum of 12"
(305mm) away from pipes, conduits or other obstructions to allow for sway during a
seismic event.
4. GENERAL DESCRIPTION
Thomson Technology TS 840 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.
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 840 series Automatic Transfer Switch is rated for 100% system load and requires
upstream over current protection. The TS 840 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 6of this manual for
detailed information on over current protection.
The TS 840 series transfer switches use a type TSC 80 microprocessor based controller which
provides all necessary control functions for fully automatic operation. The TSC 80 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 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

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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 840 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
TS8 4
1-3. SERIES 12. APPLICATION 18. UTILITY SWITCHING DEVICE
TS - TRANSFER SWITCH A - STANDARD K - MOLDED CASE SWITCH (100 - 800 A)
B - SERVICE ENTRANCE M - MOLDED CASE SWITCH C/W THER-MAG
4 & 5. MODEL
TRIP (100-200A)
84 - 840 SWITCH 13. OPERATION TYPE
N - MOLDED CASE SWITCH C/W ELECTRONIC
1 - OPEN TRANSITION TRIP (250-800A)
6. POLES
2 - 2 POLE
14 . SAFETY STANDARDS
19. GENERATOR SWITCHING DEVICE
3 - 3 POLE A - UL 1008 K - MOLDED CASE SWITCH (100 - 800 A)
B - CSA C22.2 NO 178 M - MOLDED CASE SWITCH C/W THER-MAG
7. CONFIGURATION TYPE TRIP (100-200A)
A - ATS
15 . VOLTAGE
N - MOLDED CASE SWITCH C/W ELECTRONIC
1
f
3 WIRE
TRIP (250-800A)
8 - 11. AMPERAGE
D - 120/240
0100
3
f
4 WIRE
(GROUNDED NEUTRAL) 20. POWER CONNECTIONS
0150 E - 120/208 A - STANDARD
0200 G - 120240 (DELTA)
0250
21. ATS CONNECTION CONFIGURATION
0400 16. CONTROLLER A - STANDARD
0600 1 - TSC80
0800
17. ENCLOSURE TYPE
D - NEMA3RSD, ASA #61 GREY

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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 840 (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).
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 preset values (adjustable from 70% to 95% of nominal), the engine warm-up

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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 transfer controller will initiate an engine start signal and will permit transfer

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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 alarm signal is manually reset.
Refer to the TSC 80 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 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 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.
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

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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.
c) Failure of one or more of the sensing/logic contacts. A qualified
service technician is required to trouble shoot this specific condition.

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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.
If the position of the transfer switch mechanism is not in the "neutral
position", manually operate the transfer switch mechanism by inserting
the manual 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.
3. Close the transfer switch door securely using a suitable tool. Lock the
door in the closed position and remove the key.
WARNING!
Failure to positively lock closed and secure the
transfer switch door may result in serious
personal injury or death due to electrical
shock.
4. 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.
5. To re-energize 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.

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5.3. TEST MODES
The transfer switch may be tested utilizing the TSC 80 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 840 series of Automatic Transfer Switches may be supplied with or
without integral over current protection as described below:
6.1. STANDARD TS 840 AUTOMATIC TRANSFER SWITCH
The standard TS 840 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 840 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 840 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.
6.2. OPTIONAL TS 840 AUTOMATIC TRANSFER SWITCH WITH INTEGRAL
OVER CURRENT PROTECTION
TS 840 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 800A over current protection is adjustable electronic
type with long time & instantaneous trip unit elements with optional ground fault protection
elements.