SamplexPower STS-30 User manual

Transfer
Switch
30 Amps
STS-30
Please read this
manual BEFORE
operating your
transfer switch
Owner's
Manual

2 | SAMLEX AMERICA INC.
OWNER'S MANUAL | Index
SECTION 1
Safety Instructions................................................................. 3
SECTION 2
General information ............................................................. 4
SECTION 3
Layout .......................................................................... 5
SECTION 4
Description, Features and Principles of Operation ................ 7
SECTION 5
Installation and Operation .................................................... 8
SECTION 6
Troubleshooting ................................................................. 16
SECTION 7
Specications ..................................................................... 18
SECTION 8
Warranty ........................................................................ 19
Disclaimer of Liability
UNLESS SPECIFICALLY AGREED TO IN WRITING, SAMLEX AMERICA, INC.:
1. MAKES NO WARRANTY AS TO THE ACCURACY, SUFFICIENCY OR SUITABILITY OF ANY TECHNICAL OR OTHER INFORMATION
PROVIDED IN ITS MANUALS OR OTHER DOCUMENTATION.
2. ASSUMES NO RESPONSIBILITY OR LIABILITY FOR LOSSES, DAMAGES, COSTS OR EXPENSES, WHETHER SPECIAL, DIRECT,
INDIRECT, CONSEQUENTIAL OR INCIDENTAL, WHICH MIGHT ARISE OUT OF THE USE OF SUCH INFORMATION. THE USE OF
ANY SUCH INFORMATION WILL BE ENTIRELY AT THE USERS RISK.
Samlex America reserves the right to revise this document and to periodically make changes to the content
hereof without obligation or organization of such revisions or changes.
Copyright Notice/Notice of Copyright
Copyright © 2016 by Samlex America, Inc. All rights reserved. Permission to copy, distribute and/or modify this
document is prohibited without express written permission by Samlex America, Inc.

2 | SAMLEX AMERICA INC. SAMLEX AMERICA INC. | 3
1. IMPORTANT SAFETY INSTRUCTIONS
SAVE THESE INSTRUCTIONS. THIS MANUAL CONTAINS IMPORTANT INSTRUCTIONS FOR
MODEL STS-30 THAT SHALL BE FOLLOWED DURING INSTALLATION AND MAINTENANCE
OF THE TRANSFER SWITCH.
The following safety symbols will be used in this manual to highlight safety and
important information:
WARNING!
Indicates possibility of physical harm to the user in case of non-compliance.
!
CAUTION!
Indicates possibility of damage to the equipment in case of non-compliance.
i
INFO
Indicates useful supplemental information.
Please read these instructions BEFORE installing or operating the unit to prevent
personal injury or damage to the unit.
WARNING!
- Connections for standby / backup power to a building / RV System using the
Transfer Switch must be made by a qualied electrician and must comply with
all applicable Electrical Codes.
- Before starting installation, disconnect all live sources of power. Make sure
that the Generator is off, the external shore power cord is unplugged, and
the Inverter, if any, is shut off.
- The unit is not weather proof and should be mounted in a cool, dry and
protected environment.
- To prevent exposure to contaminants, do not mount the transfer switch in
an engine compartment, under kitchen sink drains or water pipes, within the
battery compartment, or in any compartment designed for storage of am-
mable liquids such as gasoline.
SECTION 1 | Safety Instructions

4 | SAMLEX AMERICA INC.
SECTION 2 | General Information
2.1 FUNCTION OF A TRANSFER SWITCH
In case of failure of the main AC power source like the Grid power, it is desirable to
switch the critical AC loads to a standby / back up AC power source like a Generator
or an Inverter. The switching action should ensure that only one AC power source is
connected to the AC loads at any one time and that the Grid power and the Generator /
Inverter output power are never connected in parallel but remain isolated
The electrical loads cannot be connected in parallel with the Generator / Inverter and
Grid power at the same time. This will cause the following damage and safety hazards:
- The Grid line voltage is normally "stepped down" by a transformer before entering
the home / RV park / campground. The transformer will work in reverse when
voltage is sent through it in the opposite direction and will "step up" the voltage
fed back into it. If the Grid power is interrupted (say the feeder section upstream is
switched off by workers for repairs), the Generator / Inverter will feed voltage back
into the Grid power lines, this voltage will be stepped up by the transformer and
will electrocute the workers that come into contact with the Grid lines.
- If the Grid power and the Generator / Inverter are alive at the same time, the Grid
power will be fed back into the Generator / Inverter and the Generator / Inverter
will get damaged. There is also a potential of re!
2.2 APPLICATION OF TRANSFER SWITCH IN HOMES
By installing a Transfer Switch near your Main Breaker Panel and connecting a Gen-
erator / Inverter to the Transfer Switch, you can run selected circuits from your Main
Breaker Panel for appliances such as a furnace, well pump, sump pump, refrigerator,
television, computer, printer or lighting circuit during a power outage, depending on
the capacity of your Generator / Inverter.
2.3 APPLICATION OF TRANSFER SWITCH IN RECREATIONAL VEHICLES (RVS)
RVs have both a 12 VDC House or Domestic System and a 120 VAC System. The DC
System commonly provides power for area lighting, stereo, water pumping and other
loads requiring relatively small amounts of power. The 120 VAC System powers larger
loads like microwave ovens, hot water heaters, washer /dryer, coffee machines, hair
dryers, space heaters, heating and air-conditioning (HVAC) and convenience outlets that
supply power to audio, video and entertainment systems. The domestic refrigerator
is commonly supplied by both the 12 VDC and the 120 VAC Systems and sometimes
alternatively by propane.
Inverters are also used to provide AC power for dry camping where AC Grid power is not
available or in cases where gensets are not permitted due to noise restrictions. Typically,
the Inverter only supplies AC devices that are the highest priority such as microwave,
entertainment and convenience outlets. It is not practical to run loads like hot water
heaters and HVAC systems from Inverters that are ultimately powered from batteries.

4 | SAMLEX AMERICA INC. SAMLEX AMERICA INC. | 5
Frequently, the total AC power requirement of all the system loads exceeds the
campground / RV park’s power inlet and consequently, requires the genset to power
the entire system.
Thus, there may be 3 types of AC power sources. Transfer switches are used to
congure switching of the AC power sources so that the priority of the AC sources is:
- Grid power, or
- Genset (Generator), or
- Inverter
2.4 SIZING OF TRANSFER SWITCH
Determining which circuits you will require during a power outage is the rst step in
selecting the proper backup Generator / Inverter and the transfer switch. Since most
home appliances operate intermittently, a 3000 watt Generator / Inverter and a 30 A
Transfer Switch can provide adequate power to circuits for the most common appli-
ances, such as furnace, lights, refrigerator, freezer, microwave oven, and TV.
If your home has a deep well pump with up to 1 HP motor, a 5000 Watt Generator and
50 A Transfer Switch will be required to provide the starting capacity for the pump.
Larger wattage units can be selected for simultaneous starting and operation of multi-
ple appliances.
SECTION 3 | Layout
1. 15A power cord for
connection to Inverter
(<1800 VA).
2. 15A, NEMA5-15P North
American plug
3. NEMA5-20R AC outlet for
Battery Charger or Converter
4. ¾” cable clamp for Grid
power cord / Generator cord
5. Cable clamp for Inverter
power cord
6. Grounding lug
7. Spare knockouts for ¾” cable
clamp. Additional ¾” & 1”
knockouts are provided on the
two other sides (not shown).
762
1
4
5
3
Fig. 3.1 External view and layout
SECTION 2 | General Information

6 | SAMLEX AMERICA INC.
SECTION 3 | Layout
SW1
T4
T2
R1
T6
LED1 PCB1
T5
T3
T1
T8
T7
LEGEND:
-R1: Transfer Relay
-T1: Line "L", Common
-T2: Neutral "N", Common
-T3: Line "L1", NO (Normally open contact of Transfer Relay)
-T4: Neutral "N1", NO (Normally open contact of Transfer Relay)
-T5: Line "L2", NC (Normally closed contact of Transfer Relay)
-T6: Neutral "N2", NC (Normally closed contact of Transfer Relay)
-T7: (-) Input for relay coil
-T8: (+) Input for relay coil
-SW1: DIP Switch for enabling / disabling time delay for transfer
to Generator
-OFF: Enabled - delay of 20 - 25 sec. (factory preset
condition)
-ON: Disabled - no delay
-LED1: Green LED - On when Transfer Relay R1 is energized
-PCB1: Printed Circuit Board for transfer relay control
Fig. 3.2 Internal layout of contacts of the Transfer Relay and the PCB for relay control

6 | SAMLEX AMERICA INC. SAMLEX AMERICA INC. | 7
4.1 DESCRIPTION
Transfer Switch STS-30 is designed for single phase operating voltage of 120 VAC, 60 Hz
and can handle input/ output current of up to 30 A or an Apparent Power of 3600 VA
(Apparent Power = Volts X Amps. In this case: 120 V X 30A = 3600 VA). It consists of a
Transfer Relay (R1, Fig. 3.2) and a Relay Control PCB (PCB1, Fig. 3.2) for controlling the
operation of the Transfer Relay. Figs. 3.1 & 3.2 show the layout.
4.2 FEATURES
- Can be congured for transfer between Grid / Inverter or between Grid / Generator
- Multiple ¾” and 1” knockouts (7, Fig. 3.1) have been provided on all the sides for ease
of routing the input and output cables
- Consists of heavy duty 110 VDC, Double Pole Double Throw (DPDT) Relay (R1, Fig 3.2)
for switching both the Line and Neutral
- Internal DIP Switch ( SW1, Fig 3.2) for enabling or disabling delayed transfer
to Generator
- Internal LED (LED1, Fig 3.2) for indicating energized condition of the Transfer Relay
(R1, Fig 3.2) and for diagnostics
4.3 PRINCIPLE OF OPERATION
Please refer to Fig 3.2.
Relay R1 is a Double Pole Double Throw (DPDT) relay and is used to switch power from
one source to the other. The relay coil is energized as soon as 110 VDC is fed from circuit
board PCB1 to terminals T7 and T8. When the relay coil is de-energized, the common
contact terminals T1 and T2 are connected to the Normally Closed (NC) contact terminals
T5 and T6 respectively. When the relay coil is energized, the common contact terminals T1
and T2 switch over to the Normally Open (NO) contact terminals T3 and T4 respectively.
The relay coil (R1, Fig 3.2) operates at 110 VDC. This voltage is generated and controlled
by the circuitry located on PCB1. 120 VAC is tapped from contact terminals T3 and T4, is
rectied and made available to the relay coil terminals T7 and T8 through a Time Delay
Circuit. DIP Switch SW1 located on the PCB1 is used to enable or disable the Time Delay
Circuit. The default, factory preset position of SW1 is OFF and the Time Delay Circuit is
enabled. When the Time Delay Circuit is enabled (SW1 in OFF position), 110 VDC control
signal for energizing the relay coil is delayed by around 20 to 25 sec from the time 120
VAC is made available at the NO contact terminals T3 and T4. When the Time Delay Circuit
is disabled (SW1 in ON position), the 110 VDC control signal for energizing the relay coil
is made available to terminals T7 and T8 as soon as 120 VAC is made available at the NO
terminals T3 and T4.
SECTION 4 | Description, Features and
Principle of Operation

8 | SAMLEX AMERICA INC.
SECTION 4 | Description, Features and
Principle of Operation
As soon as the 110 VDC control signal is fed to terminals T7 and T8 of the relay coil,
the green LED 1 lights up indicating that the relay coil has energized.
The delay of around 20 to 25 sec is required when the AC load is transferred to the
Generator. The Generator should never be started on load. Also, the Generator takes
around 20 to 25 sec to stabilize in voltage and frequency.
SECTION 5 | Installation and Operation
5.1 MOUNTING LOCATION
The unit can be installed (i) near the power cord entry of the RV or (ii) near the
location of the Generator output on the line side of its main Distribution Panel, or
(iii) on the load side between the Main Panel and a Sub Panel, allowing switching for
either the entire electrical load or only designated circuits. Typical locations include
under counter cabinets, below closet compartments, inside the bed pedestal or cabinets,
overhead cabinets, under-oor storage compartments accessed from the vehicle
exterior, etc. The chosen location must be accessible after installation is complete to
facilitate future servicing.
5.2 CABLE ENTRY AND EXITS
A number of ¾” and 1” knockouts have been provided on all the sides (7, Fig 3.1) for
ease of routing the input and output cables. Choose a knockout that will facilitate
installation and service within the selected mounting area. Use 3/4” or 1” cable clamps
as necessary to clamp the cables entering and exiting the box.
5.3 MOUNTING
Mount the unit with screws through holes in the bottom of the unit. The unit should be
screwed to a solid surface rmly enough to hold its weight during vehicle operation.
5.4 MAKING ELECTRICAL CONNECTIONS
1. Attach an 8 gauge Earth Ground wire to the transfer switch Chassis Ground Lug
(6, Fig 3.1). 4 studs with serrated lock washers and nuts have been provided on the
inner bottom of the case to make Earth grounding connections from the inner side.
These are marked:
2. The color code for 120 VAC wiring is as follows:
• The "Grounding" wire is bare or Green
• The "Neutral" wire is White
• The "Line" wire is Black

8 | SAMLEX AMERICA INC. SAMLEX AMERICA INC. | 9
3. A ¾” cable clamp has been provided (4, Fig. 3.1). Additional ¾” and 1” knockouts
have been provided for convenience. Please ensure that a cable clamp is used for
cable entries.
4. For making rm connections to the terminals (T1 to T6, Fig 3.2) of the Transfer
Relay, please crimp appropriate size of insulated ring / spade lugs on the ends of
the conductors of the cables.
5. Connect the Grounding Conductors (Green / bare wire) of the cables to the spare
Grounding Studs marked ( )
6. Two or more conductors can be spliced together using the appropriate size of
twist-on type of cone shaped, plastic insulated Wire Nut Connector - also called
"Marrette" (See Fig. 5.1). The connector twists over the wires to make a tight
connection around the wires. A square-cut spring inside provides tension on the
wires to hold them secure. As you tighten the wire connector, the spring draws
tighter around the wires.
Fig. 5.1. Twist-on type of Wire Nut Connector.
To splice the wire leads using the Wire Nut Connector, hold the
bare ends of the wires parallel to each other so that the wire
tips are even, then secure with the wire nut. Use the proper size
nut. Manually tighten nuts as tightly as possible. Verify that all
connections are tightened.
5.5 INSTALLATION CONFIGURATIONS
5.5.1 Pre-wired Conguration
This Transfer Switch has been especially pre-wired for ease of connections for setting up
a backup power / UPS (Un-interruptible Power Supply) system with Grid / Shore Power
as the Primary Source and the Inverter as the Backup Source. The System will require an
Inverter, a Battery Charger and batteries. General overview and features for the pre-
wired conguration are given below (Refer to Fig. 5.2).
- Primary AC power of up to 3600 VA (30A at 120 VAC) can be provided by Grid (also
called Shore Power Cord or “Cord” in RVs). This is connected to the Normally Open
Contacts T3 and T4. NEMA-20R Duplex Outlets (3, Fig. 3.1) have been provided
on the side of the unit for ease of connecting a Battery Charger or Converter (on
board Converter in RVs).
- Back-up power of up to 3600 VA (30A at 120 VAC) can be provided from an Invert-
er. A 15A power cord (1, Fig 3.1) with a 15A, NEMA5-15P plug (2, Fig. 3.1) has been
provided to allow easy, pluggable connection to Inverter of up to 1800 VA capacity.
For connecting higher capacity Inverter > 1800A & up to 3600 VA, replace the
wiring with AWG#10/3 and connection arrangement rated for 120 VAC, 30A.
SECTION 5 | Installation and Operation

10 | SAMLEX AMERICA INC.
SECTION 5 | Installation and Operation
LEGEND:
T1 LINE “L”, COMMON
T2 NEUTRAL “N”, COMMON
T3 LINE “L1”, NO
(NORMALLY OPEN)
T4 NEUTRAL “N1”, NO
(NORMALLY OPEN)
T5 LINE “L2”, NC
(NORMALLY CLOSED)
T6 NEUTRAL “N2”, NC
(NORMALLY CLOSED)
T7 (–) INPUT FOR RELAY COIL
LED1 GREEN LED: ON WHEN
LED IS ENERGIZED
SW1 TIME DELAY SWITCH
OFF: DELAY ENABLED (DEFAULT)
ON: DELAY DESABLED
T8 (+) INPUT FOR RELAY COIL
GROUNDING
STUD AND NUT
PCB1 CIRCUIT BOARD
FOR CONTROL OF
RELAY R1
ATTACHED 15A AC POWER CORD
WITH NEMA5-15P PLUG
ON LED1
T5
T7 T8
T1 T2
T3
20 A
FUSE
NEMA5-20R
DUPLEX
AC OUTLET
WHITE WIRE -
NEUTRAL “N”
BLACK WIRE - LINE “L”
GREEN WIRE - GROUND
T4
T6
SW1
PCB1
RELAY R1
+
_
ACL ACN
BLACK WHITE
AC INPUT TO NORMALLY
CLOSED (NC) CONTACT
TERMINALS T5 & T6
Fig. 5.2 Pre-wired connections
5.5.2 Switching Between Grid (Primary Source) and Inverter (Backup Source)
Please refer to Fig 5.3.
ON LED1
LEGEND:
T1 LINE “L”, COMMON
T2 NEUTRAL “N”, COMMON
T3 LINE “L1”, NO
(NORMALLY OPEN)
T4 NEUTRAL “N1”, NO
(NORMALLY OPEN)
T5 LINE “L2”, NC
(NORMALLY CLOSED)
T6 NEUTRAL “N2”, NC
(NORMALLY CLOSED)
T7 (–) INPUT FOR RELAY COIL
T8(+) INPUT FOR RELAY COIL
PCB1 CIRCUIT BOARD FOR
CONTROL OF RELAY “R1”
GROUND STUD AND NUT
LED 1 GREN LED: ON WHEN
RELAY IS ENERGIZED
SW1 TIME DELAY SWITCH
ON - DELAY DISABLED
T5
T7 T8
T1 T2
T3
20A
FUSE
BLACK, “L”
FROM INVERTER
BLACK, “L”
FROM GRID
WHITE, “N”
FROM INVERTER
GREEN, “GND”
FROM INVERTER
BATTERY
SIDE FUSE
FOR
INVERTER
BATTERY SIDE
FUSE FOR
CHARGER
AC INPUT FROM INVERTER
TO NORMALLY CLOSED (NC)
CONTACT TERMINALS T5,T6
OUTPUT TO
AC BREAKER
PANEL
DISCONNECT AC INPUT OF THE ON-BOARD CONVERTER IN
THE RV FROM THE MAIN BREAKER PANEL AND CONNECT IT
TO THE NEMA5-20R AC OUTLET ON THE TRANSFER RELAY
EXISITING ON-BOARD CONVERTER
30 A MAIN
BREAKER PANEL
INPUT FROM GRID / SHORE POWER CORD (RV) TO
NORMALLY OPEN (NO) CONTACT TERMINALS T3,T4
30
MAIN
BRANCH CIRCUITS
ON-BOARD
CONVERTER
IN THE RV
1 2 3 4 5
BATTERY
CHARGER OR
CONVERTER
BATTERY
–
+
–
+
INVERTER
–
+
–
+
T4
T6
SW1
TO BATTERY
–
+
NEMA5-20R
AC OUTLET
PCB1
ACL ACN
ATTACHED 15A AC POWER
CORD WITH NEMA-15P
PLUG FOR FEEDING
AC INPUT FROM INVERTER
GREEN OR
BARE, “GND”
TO PANEL
WHITE
“N” FROM
GRID
GREEN OR
BARE, “GND”
FROM GRID
BLACK, “L”
TO PANEL
WHITE
“N” TO
PANEL
RELAY
R1
+
_
BLACK, “L”
WHITE, “N”
GREEN OR BARE, “GND”
Fig. 5.3 Switching Between Grid / Shore
Power and Inverter - (Grid / Shore
Power is the Primary Source)