phase monitor.
The delayed transition transfer switch is ideally suited for
pumping stations, sewage treatment plants, hospital
X
-ray
equipment, or wherever the bulk of the load being
controlled consists of large motors and/or transformers.
Major
UPS
manufacturers strongly recommend the use of
delayed transition type transfer switches to ensure proper
operation of their rectifier circuit and battery system. The
ZTSD
Model allows a
UPS
system sufficient delay to recognize
a power failure and transfer to batteries, acknowledge the
return of power and allow the rectifier to walk-on to the
new source, reducing any transfer anomalies.
Except for the delayed transition period, the perform-ance,
operating capabilities, ratings,
UL
listings, withstand current
values and available options are identical to those of the
GE
Zenith
ZTS
Series Automatic Transfer Switches.
The
ZTSD
incorporates all of the important features of the
standard
ZTS
Series switches. In addition, its unique design
incorporates features oriented toward its specific operation.
Application Information
When transferring large motors,
UPS
systems and/or
transformers between two sources of power that have the
potential to be unsynchronized, consideration must be
given to the elimination or reduction of transients. These
may occur when loads are disconnected from the first power
source and immediately connected to the second source.
When a running motor is suddenly disconnected from its
power source, the residual voltage developed due to
generator action will decrease in amplitude and frequency
as the motor slows down. Depending on the type number
and application of the motors involved, the decaying action
may take a considerable amount of time. Similarly when a
transformer is disconnected from the line, time is required
for its magnetic field to collapse. Release of stored energy
in the transformer generates a surge even though the two
power sources are in synchronism when a transfer is
initiated. The transient caused by the momentary high current
Model ZTSD
Delayed Transition Transfer Switches
Supplement to ZTS Series Product Bulletin
Product Bulletin
GE
Zenith Controls
e
flow described above can exceed the instantaneous trip settings
of protective devices in the system and can be severe enough to
trip circuit breakers cause damage to motor shafts couplings, etc.
One solution to this problem is to introduce a delay in the
transition between two live sources. The
GE
Zenith
ZTSD
Model Delayed Transition Transfer Switches have been
designed expressly for this purpose.
The advantages of using the
ZTSD
Model when trans-ferring
large motor and/or transformer loads are:
Description and Operation
The operation of the
ZTSD
Model Delayed Transition
Transfer Switch is identical to the
GE
Zenith
ZTS
Model
with the exception of the drive mechanism.
Upon failure or reduction of the normal source, and the
availability of the emergency source, the drive solenoid
is energized and pulls the main contacts out of the normal
position and locks them mechanically in the open transition
position. An adjustable time delay is then energized. After
the preset time has elapsed, the drive solenoid is energized
and pulls the main contacts out of the transition position
and locks them mechanically in the emergency closed position.
The emergency power source is now feeding the load.
When the voltage sensing detects the restoration of the
normal source for a predetermined time period, the drive
solenoid is energized and pulls the main contacts from the
emergency position and locks them mechanically in the
open transition position. After the preset time delay has
elapsed, the drive solenoid is energized and pulls the
main contacts out of the open transition position and
locks them mechanically in the normal closed position.
The normal power source is now feeding the load.
All voltage and frequency sensing controls, disconnect plug,
test switch, time delays and other accessories supplied
on the
ZTS
Series are also supplied on the
ZTSD
Model.
Specification
Assistance
GE
Zenith offers a complete
range of product guide
specifications to help you
determine your needs.
For more information,
please consult your local
GE
Zenith representative,
our factory or our website
at
www.geindustrial.com
. Consistent operation under all
conditions, including manual
(pushbutton) operation Operation is totally independent
of the synchronism of the power
sources, eliminating the need for
in-phase monitors or extensive
motor disconnect control wiring
between the transfer switch and
motor control centers The delayed transition func-
tion adapts itself for use in
multiple generator systems and
paralleling systems to permit
load shedding by switching the
main contacts to a center-off
or disconnected position Allows
UPS
systems to func-
tion properly while switching
between line input sources Model ZTSD
Specifications / Power Connection Terminals
40, 80
100, 150
225, 260, 400
600
1600
2000
3000
4000
800, 1000, 1200
2, 3
4
2, 3
4
3
4
3
4
3
4
2, 3
4
46 (117)
46 (117)
66 (168)
74 (188)
90 (229)
90 (229)
90 (229)
90 (229)
90 (229)
90 (229)
74 (188)
74 (188)
24 (61)
24 (61)
24 (61)
30 (76)
30 (76)
36 (91)
30 (76)
36 (91)
40 (102)
46.5 (118)
30 (76)
40 (102)
14.13 (36)
14.13 (36)
19.75 (50)
19.75 (50)
48 (122)
48 (122)
48 (122)
48 (122)
60 (152)
60 (152)
19.75 (50)
19.75 (50)
A
A
B
B
C
C
C
C
C
C
B
B
80 (36)
85 (39)
185 (84)
205 (93)
365 (166)
470 (213)
485 (220)
690 (313)
790 (358)
1045 (474)
210 (95)
230 (104)
200 (91)
205 (93)
400 (181)
450 (204)
1030 (467)
1190 (540)
1150 (522)
1415 (642)
1615 (732)
1870 (848)
475 (215)
560 (254)
1 7
1 8
1 8
1 8, 10, 11
1 11
1 8
Ampere
Rating
Poles
Height
(A)
Width
(B)
Depth
(C)
Reference
Figure
Open
Type
NEMA 1
Application Notes
NEMA 1 Enclosed
Weight
Model ZTSD Transfer Switches
1. Metric dimensions (cm) and weights (Kg) shown in parenthesis adjacent
to English measurements in inches and pounds.
2. Includes 1.25" door projection beyond base depth. Allow a minimum of 3"
additional depth for projection of handle, light, switches, pushbuttons, etc.
3. All dimensions and weights are approximate and subject to change
without notice.
4. Special enclosures (NEMA 3R, 4, 12, etc.) dimensions and layout may differ.
Consult the
GE
Zenith factory for details.
5. Normal and emergency may be ordered inverted on any switch.
The load may be inverted 600-1200 amps. Consult the factory for details.
6. Special lug arrangements may require different enclosure dimensions.
For certified drawings, contact the
GE
Zenith factory.
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. 4000 amp depth dimension shown is standard. Depending on your
cable/conduit requirements you may desire a deeper enclosure.
Consult the
GE
Zenith factory for further details.
10. Lug adapters for 3000-4000 amp limits may be staggered length for ease
of entrance. Consult the
GE
Zenith factory for details.
11. Ventilation louvers on both sides of enclosure at 3000 and 4000 amps.
One must be clear for airflow with standard cable connections.
Application Notes:
A
C
B
Figure A
A
C
B
Figure B
Notes:
*
Line and load terminals are located in rear and arranged for bus bar connection.
Terminal lugs are available at additional cost. Contact factory 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. Normal and emergency may be ordered inverted on any switch.
Load may be inverted 600-1200 amps. Consult the factory for details.
es:
4. Lug adapters for 3000-4000 amp units may be staggered length for ease
of entrance. Consult the factory for details.
5. Special lug arrangements may require different enclosure dimensions.
For certified drawings, contact the
GE
Zenith factory.
AL-CU UL Listed Solderless
Screw-Type Terminals for
External Power Connections
Switch
Normal,
Switch
Normal
Size
Emergency,
Size
Emergency,
Amps
& Load Terminals
Amps
& Load Terminals
Cables/
Wire
Cables/
Wire
Pole
Ranges
Pole
Ranges
40-150
1
#8 to 3/0
800/1000
4
#2 AWG to
AWG
/1200
600 MCM
225
1
#4 AWG to
1600
600 MCM
260
1
#4 AWG to
2000
600 MCM
400
1
#4 AWG to
3000
600 MCM
600
2
#2 AWG to
4000
600MCM
*
A Product of GE Industrial Systems
General Electric Company
830
West
40
th
Street, Chicago,
IL 60609 USA
773 299-6600
, Fax:
630 850-6899
www.geindustrial.com
g
GE
Zenith Controls
Electrical Ratings Ratings 40 to 4000 amperes 2, 3 or 4 Poles Open type,
NEMA
1,
3
R
, 4, 4
X
and 12 Available to 600
VAC
,
50 or 60 Hz Suitable for emergency and
standby applications on all
classes of load,
100% tungsten rated through
400 amps UL
1008 listed at 480
VAC CSA C
22.2 No. 178 certified at
600
VAC IEC
947-6-1 listed at 480
VAC
Performance Features Adjustable center-off time to
meet specific installation
requirements High close-in and withstand
capability Temperature rise test per
UL
1008 conducted after overload
and endurance tests -
exceeds
UL
requirements Available in
ZTSD
(utility-
generator),
ZTSDU
(utility-
utility),
ZTSDG
(generator-
generator) and
ZTSDM
(manual) configurations
Design and
Construction Features Mechanically interlocked
center-off position for load
decay Electrically operated,
mechanically held by
a simple, over-center
mechanism Segmented silver tungsten
alloy contacts with separate
arcing contacts on all size