IB140058EN
For more information visit: www.eaton.com
Instructional Booklet
Effective: March 2016
Page
3
O&M Manual for 30-1000 Amperes
Manual Transfer Switch
1.2 General Information
Transfer switches are used to protect critical electrical loads
against loss of power. The load's normal power source is backed
up by a secondary (emergency) power source. A transfer switch is
connected to both the normal and emer- gency power sources and
supplies the load with power from one of these two sources. In
the event that power is lost from the normal power source, the
transfer switch transfers the load to the secondary (emergency)
power source. Transfer can be automatic or manual, depending
upon the type of transfer switch equipment being used. Once nor-
mal power is restored, the load is automatically or manually trans-
ferred back to the normal power source, again depending upon the
type of transfer equipment being used (Figure 2)
1.2.1 Transfer Switch Types
Four types of basic transfer switch equipment are available:
Automatic Transfer Switch
Automatic transfer switches automatically perform the transfer
function. They consist of three basic elements:
1. Main contacts to connect and disconnect the load to and from
the power source.
2. A mechanism to transfer the main contacts from source to
source.
3. Intelligence/supervisory circuits to constantly monitor the con-
dition of the power sources and thus provide the intelligence
necessary for the switch and related circuit operation.
Basic Transfer Switch
The basic transfer switch is designed for use with customer fur-
nished controls. It is similar in design to the automatic version
except the intelligence circuit (logic panel) and voltage selection
panel are omitted. All automatic sensing devices, relays or solid-
state devices are the customer's responsibility.
Figure 2. Typical Load Transfer Switch (Circuit Breaker Type)
Schematic.
Manual Transfer Switch (Manually Operated)
Manual transfer switches provide the main contacts and the trans-
fer mechanism to effect the transfer of the main contacts from
source to source. Transfer of power, however, is accomplished by
true hand operation (not power assisted) of the transfer switch.
This switch is similar to the basic switch in that an intelligence cir-
cuit and a motor driven mechanism are not part of the design.
1.2.2 Design Configuration
The Eaton Transfer Switch is a rugged, compact design utilizing
molded case switches to effect the transfer of essential loads
from one power source to another (Figures 3, 4 and 5). Molded
case switches are interlocked to prevent both switches from being
closed at the same time. The versatile design, in addition to stan-
dard transfer functions, offers an optional integral thermal and
short circuit protection in either or both switching devices.
Molded case switches and the associated transfer mecha- nism
are usually mounted vertically in the assembly. The vertical config-
uration (225 - 1000 amperes) is accomplished by utilizing a posi-
tive, metallic transfer and interlocking system between the molded
case switches. A horizontally mounted transfer mechanism is uti-
lized with transfer switches 30 - 150 amperes.
The Eaton Transfer Switch was designed with installation ease
and simplified maintenance in mind. Three main panels comprise
the automatic transfer switch design:
•
Power Panel
•
Voltage Selectin Panel
•
Logic Panel
Each panel is independently mounted with interconnecting wiring
terminated in connector plugs to permit individual door or panel
removal without disturbing critical connec- tions. Enclosure
mounting is simplified by utilizing top and bottom mounting
flanges with elongated mounting holes.
For the vertical design, installed power panel positioning bolts,
elongated mounting holes and pre-tapped inserts insure proper
power panel mounting after initial enclosure installation or when
switching from top to bottom entry and vice versa. Refer to Sec-
tion 4 for mounting and modification details.
1.3 Transfer Switch Catalog Number Identification
Transfer switch equipment catalog numbers provide a signifi- cant
amount of relevant information that pertains to a particu- lar piece
of equipment. The Catalog Number Identification Table (Table 1)
provides the required interpretation informa- tion. An example is
offered to initially simplify the process.
Example:
Catalog Number (bolded numbers correspond to posi-
tion headings in Table 1)
Table 1.
1 to 2 3
4
5 6
7
8
9 to 12
13
14
15
MT
V
X
KD
A
3 0300
X
S
U
The catalog number MTVXKDA30300XSU describes a Manual
transfer switch with the switching devices mounted vertically in
the enclosure. The Eaton Series CT Type HKD is used as the
switching device and is in the form of a 3-pole molded case
switch on each source. The continuous current rating of this
equipment is 300 amperes and applicable at 480 Vac, 60 Hz. The
transfer switch equipment is enclosed in a NEMAT 1 enclosure
and is both UL and CSA listed.
Emergency Source
Normal Source
Load
