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Zenith ZTS Series

Low-Voltage Automatic and
Manual Transfer Switches
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Zenith ZTS Series
Low-Voltage Automatic and Manual Transfer Switches

Since its introduction, Zenith ZTS Series of • Controls tested in accordance with:
transfer switches has become a hallmark of quality - IEEE 472 (ANSI C37.90A)
and performance. Reliability resulting from superior - EN55022 Class B (CISPR 22) (Exceeds EN55011 &
design and heavy duty construction has made the MILSTD 461 Class 3)
ZTS the industry standard for critical installations. - EN61000-4-2 Class B (Level 4)
Our emphasis on research and development, design - EN61000-4-3 (ENV50140) 10 v/m
improvements, materials, manufacturing methods, - EN61000-4-4
quality assurance and service yields products that - EN61000-4-5, IEEE C62.41 (1.2 X 50μs, 0.5 to 4 kV)
have been proven in hundreds of thousands of - EN61000-4-6 (ENV50141)
applications. - EN61000-4-11
- EN55011 :2009+A1 :2010
Subsequent to the first ZTS units installed, our
engineering staff has been dedicated to the • Equipment (Controls and Power Section)
improvement and expansion of our line. Seismic Test Qualified to:
• ZTS Automatic Transfer Switches 40-4000 Amps - IBC-2015
• ZTSD Delayed Transition Transfer Switches 40-4000 - IEEE-693-2005
Amps • Enclosures meet the requirements of:
• ZTSCT Closed Transition Transfer Switches 100- - UL 508, 50
4000 Amps - ANSI C33.76
• ZBTS Automatic Transition Bypass Switches 100- - ICS 6
4000 Amps - NEMA 250
• ZBTSD Delayed Transition Bypass Switches 100- • Quality System
4000 Amps - ISO 9001 Registered
• ZBTSCT Closed Transition Bypass Switches 100-
4000 Amps

All ZTS products meet or exceed industry

requirements allowing specification and installation
confidence.
• UL 1008 listed through 480 VAC
• CSA C22.2 No. 178 listed through 600 VAC
• IEC 947-6-1 listed through 480 VAC
• UL 1008 listed for Short Time rated 1600-3000A
(Non-bypass) ATS for 0.50 sec and 1.0 sec time
duration
Specification Assistance
• Codes and Standards ABB offers a complete range of product guide
- NFPA 70, 99, 101, 110 specifications to help you determine your needs.
- IEEE 446, 241, 602
- NEC 517, 700, 701, 702 For more information, please consult your local ABB
- NEMA ICS-10 representative, our factory or our website
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Zenith ZTS Series Automatic Transfer Switches

The Zenith ZTS Series is the building block of our lock allow for high withstand and closing ratings, far
transfer switch product line. This ruggedly built exceeding UL requirements. All ZTS units are listed
power contactor family of switches has been with UL time-based rating, coordinated breaker
specifically designed for transfer switch duty with and current limiting fuse ratings. Open and Delayed
dependability, versatility and user friendliness of Transition ATS mechanism does not allow both
prime concern. ZTS switches are available in open sources to be connected at the same time.
type construction for switchboard installation or
nema enclosed to the customer’s specifications. The —
power panel components, consisting of power Neutral Switching
switching contacts, drive mechanism and terminal The Zenith ZTS Series is available in true four pole
lugs, are mounted on a specially formed panel. Logic designs for multi-source power systems that require
devices including microprocessor control auxiliary neutral switching. The neutral contact is on the same
time delays and special accessory equipment are shaft as the associated main contacts. This ensures
assembled on the door for ease of maintenance positive operation, and avoids any possibility that
and separation from the power section. They are the neutral contact will fail to open or close, as
connected with a numbered wiring harness equipped is possible when the neutral pole is an add-on
with a disconnect plug that allows isolation of the accessory. The neutral contacts are identical to the
control panel for maintenance. main contacts, having the same current carrying and
high withstand/closing ratings as the mains. They
— are designed to break last and make first to reduce
ZTS Series Method of Operation the possibility of transients while switching the
When Source 1 voltage fails or drops to a neutral.
predetermined point (usually 80% of nominal),
if required, a circuit is closed to start the engine —
generator set. When Source 2 reaches 90% of rated Safe Manual Operation
voltage and 95% of rated frequency, the drive The ZTS manual operator consists of a large,
solenoid is energized through the Source 2 easy-to-use handle that fits securely for manual
coil control relay, causing the main contacts to operation during installation and maintenance or
disconnect the load from Source 1 and connect it in an emergency. The ZTS may be provided with an
to Source 2. After the drive solenoid has completed operator inhibit switch to disconnect the electrical
its electrical stroke and is seated, the Source 2 coil drive prior to maintenance. Fully enclosed wrap-
control relay opens to disconnect it. The around arc covers shield the main contacts and
transfer switch is now mechanically locked in the mechanical components, preventing operator
Source 2 position. When Source 1 voltage is restored exposure during manual operation.
to a predetermined point (usually 90% of nominal),
the control voltage sensing energizes. The Source 1
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side coil relay closes, and after the drive solenoid
has completed its electrical stroke and is seated, the
coil control relay opens to disconnect it. The transfer
switch is now mechanically locked in the Source 1
position.

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Drive Mechanism
All Zenith ZTS switches employ the simple “over-
center” principle to achieve a mechanically locked
position in either Source 1 or Source 2 and the high
speed drive assures contact transfer in 100ms or
less. High contact pressure and positive mechanical
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Zenith ZTS Series Automatic Transfer Switches

Transferring Large Motor or Highly Inductive Loads

Electrical Ratings
Some loads, especially large motors, receive severe
• Ratings 40 to 4000 amperes
mechanical stress if power is transferred out of
• 2, 3 or 4 Poles
phase while the motor is still rotating. Also, back EMF
• Open type, NEMA 1, 3R, 4, 4X and 12
generated by a motor may result in excess currents
• Available to 600 VAC, 50 or 60 Hz
that can blow fuses or trip circuit breakers. ABB
• Suitable for emergency and standby applications on
offers four solutions to these problems:
all classes of load, 100% tungsten rated through 400
amps
• UL 1008 listed at 480 VAC
Universal Motor Disconnect (UMD): This
• CSA C22.2 No. 178 certified at 600 VAC
load control disconnects a large motor
• IEC 947-6-1 listed at 480 VAC
via its control circuit for an adjustable
period of time prior to transfer in either
Performance Features
direction. For switching multiple motors,
• Contact transfer speed less than 100 milliseconds
Accessory UMD disconnects the motors
• High close-in and withstand capability
prior to transfer and brings them back on
• Temperature rise test per UL 1008 conducted
line sequentially.
after overload and endurance tests - exceeds UL
requirements
Accessory R50: This is an in-phase
• Available in ZTS (utility-generator), ZTSU
monitor that compares the phase
(utilityutility), ZTSG (generator-generator) and ZTSM
angle between both sources of power
(manual) configurations
and prevents transfer until the two
• Short Time rated 1600-3000A (Nonbypass) ATS for
are approximately in phase (within a
0.50 sec and 1.0 sec time duration
selfadjusting range). A high speed transfer
action, coupled with the MX series
Design and Construction Features
microprocessor control logic, ensure
• Double throw, interlocked operation
closures at or near zero degree phase
• Electrically operated, mechanically held by a simple,
difference.
over-center mechanism
• Segmented silver tungsten alloy contacts with
Series ZTSD: ABB offers delayed
separate arcing contacts on 225 amp and above
transition switching on transfer switches
• Arc quenching grids, enclosed arc chambers, and
rated 40 amperes and above–the Zenith
wide contact air gap for superior source-to-source
ZTSD Series. This programmed center-
isolation on all units
off position allows for the full decay of
• Control circuit disconnect plug and drive inhibit
rotating motors or transformer fields.
switch for safe maintenance
It can also be used for load shedding of
• Components accessible for inspection and
selected circuits or other applications
maintenance without removal of the switch or power
which require a means to disconnect the
conductors
load from either source. Major UPS system
• Mechanical indicator and contact chamber cover
manufacturers recommend delayed
designed for inspection, safety and position
transition switches for proper restart
designation
sequencing of their systems.
• Open Transition ATS perform break before make
operation on all phases
Series ZTSCT: Zenith series of closed
transition switches combine ZTSD
operation during a source failure with a
highly engineered control system that
allows momentary paralleling (100 ms) of
two acceptable sources, thereby limiting
the impact of transfer on the load.
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MX250 Series Microprocessor Controller

Enhanced Display and Settings

LEDs are used in a recognizable line configuration for continuous monitoring of
switch position. The LCD display shows source availability, exercise time delay
operation and system source condition. A simplified adjustment is featured for
voltage, frequency and time delay settings.

The control operates off a close differential 3-phase under-voltage sensing of

Source 1, factory standard setting 90% pickup, 80% dropout; under-frequency
sensing of Source 1 factory setting 95% pickup; 3-phase voltage and frequency
sensing of Source 2, factory standard setting 90% pickup voltage, 95% pickup
frequency. All factory settings are operator adjustable.

A test function is standard (fast test/load/no load) to simulate Source 1 failure -

automatically bypassed should Source 2 fail.

More Enhanced Features ensures safety in the event of a single • Simplified maintenance – major
• Available in all transfer modes: ~ phase loss components are easily replaceable
Open, Delayed & Bypass/Isolation • Voltage unbalance detection standard • Close differential under-voltage
~ Closed (with newly integrated • Extensive 2/5/10 Warranty sensing of the normal source
transition control) • Voltage and frequency sensing of the
• User-friendly programmable engine Performance Features emergency source (all settings are
exerciser, used for the engine • UL, CSA and IEC listed adjustable)
generator with or without load, at any • Ringing wave immunity per IEEE 472
interval in a one-year period (ANSI C37.90A)
• Controller can be configured to any • Conducted and Radiated Emissions
voltages for worldwide application per EN55022 Class B (CISPR 11)
• Real-time display of ATS status, (Exceeds EN55011 & MILSTD 461 Class
including active timer(s) 3)
• Multiple levels of user-defined • ESD Immunity test per EN61000-4-2
password protection Class B (Level 4)
• Serial communications allowing • Radiated RF, electromagnetic field
connectivity with other ATS's, immunity test per EN61000-4-3
paralleling switchgear, and SCADA (ENV50140) 10v/m
systems • Electrical fast transient/burst
• Time-tested synchronous logic immunity test for EN61000-4-4
automatically measures phase angle • Surge immunity test per EN61000-4-5
and frequency allowing disturbance- (IEEE C62.41) (1.2 x 50μs, 0.5 to 4 kV)
free transfer • Conducted immunity test per
• Unsurpassed statistical ATS/System EN61000-4-6 (ENV50141)
monitoring available in real-time • Voltage dips and interruption
• T3/W3 elevator pre-signal. immunity EN55011 :2009+A1 :2010
Automatically bypassed if the
selected source fails, minimizing time Technical Benefits
an elevator is without power • Separate line voltage components for
• Universal Motor Disconnect (UMD) controller isolation
sends a pre-signal, post-signal or • Inputs optoisolated for high electrical
both to any motor control center. immunity to transients and noise
Not bypassed in an outage, the UMD • Built-in electrical operator protection
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Zenith ZTS Series Accessory Group Matrix
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Zenith ZTS Series Automatic Transfer Switches

6P on retransfer
Microprocessor activated test switch (Momentary) DW (DELAYED TRANSITION ONLY)
6A Time Delay from Neutral Switch position to Source 2
Hardwired test switch (Maintained) on retransfer E Engine Start Relay
6AP ECM
Microprocessor activated test switch (Maintained) Ethernet Communication Adapter. Requires MCM
6B (Modbus) Accessory.
Hardwired test switch (Maintained Auto - Momentary EL/P
Test) Key operated Event log of last 16 events
6C F
Hardwired test switch (Maintained Auto - Maintained Fan contact, closed when engine runs.
Test) Key operated HT(1)(2)
A1 Heater and Thermostat 208/240V (1) 380/600V (2)
Auxiliary Contact S.P.D.T. - Normal (Source 1) Failure mounted and interwired in enclosure. (requires larger
A1E enclosure for 40-200A)
Auxiliary Contact S.P.D.T. - Emergency (Source 2) K
Failure Frequency Meter (Analog) - Door mounted
A3 K/P
Auxiliary Contact - closed in emergency (Source 2) Frequency Indication on the controller
Additional available (10 max.) on ZTS Series and need LNP
to be specified Center-off position LCD-Indicator
A4 L1
Auxiliary Contact - closed in normal (Source 1) LED light indicates Switch in Source 2 position
Additional available (10 max.) on ZTS Series and need L2
to be specified LED light indicates Switch in Source 1 position
AB3 L3
Auxiliary Contact - closed in bypass emergency LED light indicates Source 1 available
(Source 2) (S.P.D.T.) (Standard up to 400A) Additional L4
available (10 max.) on ZBTS Series and need to be LED light indicates Source 2 available
specified ZNET901A
AB4 Modbus Annunciator
Auxiliary Contact - closed in bypass normal (Source 1) M1
(S.P.D.T.) (Standard up to 400A) Additional available Single Phase Amp Meter (Analog)
(10 max.) on ZBTS Series and need to be specified M2
CALIBRATE Three Phase Amp Meter (Analog)
Microprocessor activated calibration feature M90
CDP EPM2200 True RMS Digital Meter with display (Amps,
Programmable exerciser daily, 7/14/28/365 days user- Volts, Power, Energy, Power Factory and Frequency). 3
selectable, with or without load Line LED Display. 50/60 Hz Universal Operation. 1 or 3
CDT phase. Standard Modbus RTU RS485 communications
Exerciser no load timer capability. 40 - 1200 Amps.
CTAP M90A
Chicago transfer alarm panel mounted in door of Adds Pre-Wiring for Enervista Viewpoint Monitoring
enclosure. Includes 3 aux. contacts and fuse. of M90 Accessory & ATS Status using Modbus RS485
DS Serial Communications
Disconnect Switch. Disconnects source voltage to M90B
transfer power panel. Adds Pre-Wiring for Enervista Viewpoint Monitoring
DT (DELAYED TRANSITION ONLY) of M90 Accessory & ATS Status using Ethernet TCP/IP
Time Delay from Neutral Switch position to Source 1 Communications
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Zenith ZTS Series Automatic Transfer Switches

M91 S5P
EPM6000 True RMS Digital Meter with display (Amps, Microprocessor programmable auto/manual
Volts, Power, Energy, Power Factory and Frequency, retransfer selection for transferring to Normal (Source
THD). Certified energy and demand metering. Meets 1) (includes controller softkey for YN accessory)
ANSI C12.20 and IEC 687 Accuracy Classes. Front IrDA S12P
Port Laptop Connection. Standard Modbus RTU RS485 Microprocessor programmable auto/manual transfer
or DNP 3.0 communications capability. selection for transferring to Normal (Source 1) and
M91A Emergency (Source 2) (includes controller softkey for
Adds Pre-Wiring for Enervista Viewpoint Monitoring YN & YE accessory)
of M91 Accessory & ATS Status using Modbus RS485 S13P
Serial Communications Microprocessor activated commit/no commit on
M91B transferring to Emergency (Source 2) (with enable/
Adds Pre-Wiring for Enervista Viewpoint Monitoring disable settings)
of M91 Accessory & ATS Status using Ethernet TCP/IP S14
Communications Keyed selector switch for retransfer to normal-test-
MCM auto
Modbus RTU Communication Module SW1
N1 Auto/Off/Start Engine control selector - Door
Running Time Indicator - Door mounted mounted (keyed or non-keyed operation available)
N2 SW2
Operation Counter - Door Mounted Auto/Off Engine control selector - Door mounted
P1 (keyed or non-keyed operation available)
Engine Start Timer (adjustable to 6 sec.) SW3
P2 Source Priority Selector Switch - Door mounted Allows
Engine Start Timer (adjustable to 300 sec.) selection of Source 1 or Source 2 to be the Prime
Q2 Source. Transfer Switch will transfer to selected Prime
Peak shave/remote load test/area protection - Input Source if that Source is available. (keyed or non-keyed
Relay (Need to specify voltage - 120 VAC, 24 VAC, 24 operation available)
VDC - 120V default standard) T
Q3 Retransfer to Normal (Source 1) adjustable time delay
Inhibit transfer to emergency (Source 2) Load add T3/W3
Input Relay (Need to specify voltage - 120 VAC, 24 VAC, Pre-signal contact on transfer to Normal (Source 1) or
24 VDC - 120V default standard) Emergency (Source 2) during test
Q7 U
Inhibit transfer to normal (Source 1) - Input Relay Engine stop /cool adjustable cool down timer
(Need to specify voltage - 120 VAC, 24 VAC, 24 VDC - UMD/A62
120V default standard) Pre and post transfer output adjustable time range.
R1-1/R1-3 Functions in both directions. Includes 2 circuits.
Over Voltage sensing for normal (Source 1) single (R1- (Additional circuits available).
1) or three (R1-3) phase VI
R15/R15D Voltage imbalance between phases (3 Phase only)
Load Shed. Should Source 2 become overloaded, an W
external signal can be given to ATS to transfer to the Adjustable time delay on transfer to Emergency
Neutral or dead Normal (Source 1) position. (Source 2)
R16 YEN/ YER
Phase rotation sensing of Normal (Source 1) and Bypass transfer timers function (soft key switch in
Emergency (Source 2) microprocessor)
R50
In Phase monitor between Normal (Source 1) and
Emergency (Source 2) to allow transfer
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Zenith ZTS Series Dimensional Specifications / Power Connection Terminals

ZTS Model, Dimensions and Weights Application Notes:

NEMA 1 Weight 1. Metric dimensions (cm) and weights (Kg)
Ampere Reference Application shown in parenthesis adjacent to English
Rating Poles Height (A) Width (B) Depth (C) Figure Open Type NEMA 1 Notes
2, 3 57 (26) measurements in inches and pounds.
40, 80,
24 (61) 18 (46) 11 (28) 21 (10) 1 - 7, 11-14
100, 150 4 60 (27) 2. Includes 1.25" door projection beyond base
A
225, 260, 2, 3 70 (32) 165 (75) depth. Allow a minimum of 3" additional
46 (117) 24 (61) 14 (36) 1 - 7, 12-14
400 4 75 (34) 170 (68)
depth for projection of handle, light,
2, 3 166 (75) 380 (172
600 1 - 8, 12-14 switches, pushbuttons, etc.
4 185 (84) 430 (195)
800, 2, 3
74 (188) 40 (102) 19.5 (50) B
190 (86) 455 (206)
3. All dimensions and weights are approximate
1000, 1 - 8, 12-13 and subject to change without notice.
1200 4 210 (95) 540 (245)
3 740 (336) 1375 (624) 4. Special enclosures (NEMA 3R, 4, 12, etc.)
1600,
2000 4 830 (376) 1480 (671) dimensions and layout may differ. Consult
90 (229) 35.5 (90) 48 (122)
3 740 (336) 1375 (624) ABB for details.
3000 C 1-13
4 830 (376) 1480 (671)
5. Normal and emergency may be ordered
3 770 (349) 1595 (723)
4000 90 (229) 46.5 (118) 60 (152) inverted on any switch. The load may be
4 1025 (465) 1850 (839)
inverted 600-1200 amps. Consult ABB for
details.
6. Special lug arrangements may require
different enclosure dimensions. For certified
drawings, contact ABB.
7. Packing materials must be added to weights
shown. Allow 15% additional weight for
cartons, skids, crates, etc.
8. Add 4" in height for removable lifting lugs.
9. Lug adapters for 3000-4000 amp limits may
be staggered length for ease of entrance.
Consult ABB for details.
10. Louvers must be clear for airflow with
standard cable connections.
11. A ZTS 40-150A, when ordered with the
following options, will require a larger
enclosure: UMD, Digital Meter, HT, HH, K,
LDS, L11, N1, N2, OCVR-1SG, OCVR-1SS, P2,
SPD, BCI, R26(D). Please contact ABB for
dimensions.
12. For Delayed and Closed Transition
dimensions and weights, refer to Publication
PB-5067 and PB-5069.
13. For Bypass/Isolation dimensions and
weights, refer to Publication PB-5068.
AL-CU UL Listed Solderless
14. AZTS, when ordered with compression lugs
Screw-Type Terminals for External Power Connections
Normal, Emergency & Normal, Emergency &
suitable for use with copper cables, will
Switch, Load Terminals Switch, Load Terminals require a larger enclosure. For 40-225A, the
Size, Amps Cables/Pole Wire Ranges Size, Amps Cables/Pole Wire Ranges
enclosure is 46" x 24" x 14" (HxWxD). For
40-80 1 #8 to 3/0 600 2 #2 to 600 MCM
260-400A, the enclosure is 66" x 24" x 19.75"
100, 150 1 #6 to 250 MCM 800, 1000, 1200 4 #2 to 600 MCM
1 #4 to 600 MCM (HxWxD). For 600A, the enclosure is 74" x
1600, 2000,
225, 260, 400 2 1/O to 250 MCM 3000, 4000 * 40" x 19.75" (HxWxD). For certifed drawings,
Notes: please contact ABB.
* Line and load terminals are located in rear and arranged for bus bar connection. Terminal lugs are
available as an accessory. Contact ABB for more details.
1. Special terminal lugs and neutral bars are available at additional cost. Contact factory and advise
cable sizes and number of conductors per pole.
2. Fully rated neutral provided on 3 phase, 4 wire system.
3. Special lug arrangements may require different enclosure dimensions. For certified drawings,
contact ABB.
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Zenith ZTS Series Ordering Information

Example
ZTSCT0B00040F-ZEC01ZVC40MSTD
This number string shows the correct format for a ZTS Model Automatic Transfer Switch with closed transition, an Entelli-Switch 250 microprocessor
control unit, Utility - Generator, 400 amps, 4 pole, NEMA Type 1 enclosure, 120/208V 3φ, 4 wire, 60 Hz system with the standard group of accessories.

Z T S C T 0 B 0 0 0 4 0 F - Z E C 0 1 Z V C 4 0 M S T D
1 2 3 4 5 6 7 8

1 Model/Type 7 Operational voltage

ZTS000 Standard (Open Transition) AB Consult table below

ZTSD00 Delayed Transition 8 Accessories

ZTSCT0 Closed Transition MSTD

ZBTS00 Standard (Open Transition) w/Bypass MEXE

ZBTSD0 Delayed Transition w/Bypass MCON

ZBTSCT Closed Transition w/Bypass MSEN

2 Control panel MSPE

B0 Entelli-Switch 250, Microprocessor, Control Unit MPSG

B1 Horizongal bypass unit with MX250 MANO

B4 High withstand panel with MX250 2) Then choose additional accessories

3 Application Available only on Bypass configuration

1)

Available for 1600-3000A Non-bypass product ONLY.

2)

0 Utility - Generator
U Utility - Utility
M Manual
A B Voltage Phase Config. Hz
G Gen to Gen
1 0 120 1 2 wire 60
4 Ampere size
2 0 120/240 1 3 wire 60
004 40 amps
2 2 110/220 1 3 wire 50
008 80 amps 3 0 240 3 3 wire 60
010 100 amps 3 1 208 3 3 wire 60
015 150 amps 3 2 220 3 3 wire 50
022 225 amps 3 5 139/240 3 4 wire 60

026 260 amps 4 0 120/208 3 4 wire 60

4 1 127/220 3 4 wire 60
040 400 amps
4 2 127/220 3 4 wire 50
060 600 amps
5 0 480 3 3 wire 60
080 800 amps 5 1 440 3 3 wire 60
100 1000 amps 5 2 440 3 3 wire 50
120 1200 amps 5 5 460 1 3 wire 50
160 1600 amps 5 7 480 1 2 wire 60

200 2000 amps 5 8 254/440 3 4 wire 60

6 0 575 3 3 wire 60
260 2600 amps 1)
6 1 347/600 3 4 wire 60
300 3000 amps
6 3 575 1 2 wire 60
400 4000 amps
7 0 277/480 3 4 wire 60
5 Switched poles 7 1 277 1 2 wire 60
B 2 Poles 7 4 266/460 3 4 wire 60
E 3 Poles 7 5 460 3 3 wire 60
F 4 Poles 8 2 380 1 2 wire 50
9 0 240/416 3 4 wire 60
6 Enclosure type
9 1 220/380 3 4 wire 60
01 Type 1 Enclosure
9 2 220/380 3 4 wire 50
12 Type 12 Enclosure
9 3 240/416 3 4 wire 50
3R Type 3R Enclosure 9 7 380 3 3 wire 60
40 Type 4 Enclosure Note: Operating voltage must be specified at
time of order. Only the most common voltages
4X Type 4X Enclosure
are shown above.
00 Open Style Unit
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Zenith ZTS Series Ordering Information

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Switch Types
• Standard: Unless otherwise noted, the standard
switch with quick transfer will be supplied.
• Delayed Transition: When ordered as the ZTSD, the
delayed transition switch offers time delay during
transfer from one position to the other. This is
primarily for transfer of large motor or inductive
loads.
• Closed Transition: When ordered as the ZTSCT, the
closed transition switch offers two basic modes of
operation. During a failure of one source or an out of
specification condition, the ZTSCT Model operates
as a standard delayed transition switch (ZTSD
Model). This sequence allows clear separation of an
unreliable source from an available one.
• Bypass: When ordered as the ZBTS, the bypass
transition switch offers a draw-out mechanism,
with electrical and mechanical interlocks for secure
removal after load bypass. In this way the transfer
switch and/or the control panel may be tested,
isolated and removed for maintenance without load
interruption.

UL 1008 Withstand and Closing Ratings

Please refer to Publication TB-1102.
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ABB Zenith Controls, Inc.

305 Gregson Drive
Cary, NC 27511
24-hour support:
ABB Technical Services
+1 (800) 637-1738

PB-5066, 19-09

© Copyright 2019 ABB. All rights reserved.

Specifications subject to change without notice.