Samlexpower STS-30 User manual

Owner's
Manual
Please read this
manual before
operating your
Transfer Switch
Transfer
Switch
30 Amps
Model: STS-30
110-17 Fawcett Rd
Coquitlam, B.C.
Canada V3K 6V2
T: 604 525 3836
F: 604 525 5221
e-mail: [e-mail]
website: www.samlexamerica.com
208-2010_STS-30_Transfer_Switch_Manual

2
INDEX
1. Introduction..................................................................................................3
2. General Information.............................. ......................................................5
3. Installation....................................................................................................6
4. Troubleshooting.................................... ....................................................13
5. Specications............................................. ............................................... 14
6. Warranty........................................... .........................................................15

3
1
INTRODUCTION
Function of a Transfer Switch
In case of failure of the main AC power source like the electric utility 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 electric utility 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 electric utility
power at the same time. This will cause the following damage and safety hazards:
-The electric utility 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
electric utility power is interrupted (say the feeder section upstream is switched off by workers
for repairs), the generator / inverter will feed voltage back into the electric utility power lines,
this voltage will be stepped up by the transformer and will electrocute the workers that come
into contact with the utility lines.
-If the electric utility power and the generator / inverter are alive at the same time, the electric
utility power will be fed back into the generator/ inverter and the generator / inverter will get
damaged. There is also a potential of re!
Application of Transfer Switch in Homes
By installing a transfer switch at your breaker box and connecting a generator/inverter to the
transfer switch, you can run selected circuits 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.
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 system and sometimes
alternatively by propane.
Inverters are also used to provide AC power for dry camping where AC shore 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.
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

4
1
INTRODUCTION
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:
-Electric utility power
-Genset (generator)
-Inverter
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 appliances, 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 multiple appliances.
Transfer Switch STS-30
Transfer Switch STS 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 30 = 3600 VA). It consists of a Transfer Relay (Fig. 2, R1) and a Relay Control
PCB (Fig. 2, PCB1) for controlling the operation of the Transfer Relay.
3
7
6
2
1
4
5
1. 15 A power cord for
connection to inverter.
2. 15 A, NEMA5-15P North
American plug
3. 15 A, dual NEMA5-15R
receptacles for battery
charger
4. ¾” cable clamp for shore
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).
Fig. 1. External view and layout

55
2
GENERAL INFORMATION
Fig. 2. Internal layout of contacts of the transfer relay and the PCB for relay control
-R1 - Transfer relay coil
-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: Delay of 20 - 25 sec.
◦On: No delay
-LED1 - Green LED - On when transfer relay coil R1 is energized
-PCB1 - Printed Circuit Board for transfer relay control
SW1
T4
T2
R1
T6
LED1 PCB1
T5
T3
T1
T8
T7

6
3
INSTALLATION
Features
-Can be congured for generator / power cord connection or inverter / alternate source
connection
-Multiple ¾” and 1” knockouts (7, Fig. 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 for switching both
the Line and Neutral. (R1, Fig 2)
-Internal DIP Switch ( SW1, Fig 2) for enabling or disabling delayed transfer to generator
-Internal LED (LED1, Fig 2) for indicating energized condition of the transfer relay coil (R1, Fig
2) and for diagnostics
Operation of the Transfer Relay (Please see Fig 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 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 T4 and T5.
The relay coil 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. When the Time Delay Circuit is enabled (SW1 in OFF
position (1). This is the factory preset 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 (DIP Switch 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.
As soon as the 110 VDC control signal is fed to the relay coil to terminals T7 and T8, 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.
Safety Instructions
-Connections for stand by / 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 laws and
electrical codes.
-Before starting installation, disconnect all live sources or 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 foreign 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 ammable liquids such as gasoline.

7
3
INSTALLATION
Mounting location
The unit can be installed near the power cord entry of the RV or near the location of the
generator output on the line side of the main distribution panel, or it can be installed on the load
side of the panel 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.
Cable entry and exits
A number of ¾” and 1” knockouts have been provided on all the sides (7, Fig 2) 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.
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.
Making electrical connections
1. Attach an 8 gauge earth ground wire to the transfer switch chassis ground lug (6, Fig 2). 4 studs
with serrated lock washers and nuts have been provided on the inner bottom of the case to make
grounding connections from the inner side .
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.
1. 3. A ¾” cable clamp has been provided (4, Fig. 1). Additional ¾” and 1” knockouts have been
provided for convenience. Please ensure that a cable clamp is used for the cable entries.
4. For making rm connections to the terminals (T1 to T6, Fig 2) of the Transfer Relay (R1, Fig 2), 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 (See Fig. 3). 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.3. 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.

8
3
INSTALLATION
Installation Congurations
Preset Conguration - General
This Transfer Switch has been especially pre-wired for ease of connections for setting up a backup
power / UPS (Un-interruptible Power Supply) system comprising of an Inverter, a battery charger and
batteries. A backup power system / UPS can be used in on-grid, off-grid and RV applications. General
overview and features for the pre-wired conguration are given below:
-The primary AC power will be the electric utility power (also called the Shore Power Cord or
“Cord” in RVs) or a generator. This is connected to the Normally Open Contacts T3 and T4. A
dual, 15 A, NEMA5-15R receptacle (3, Fig. 1) has been provided on the side of the unit for
ease of connecting the NEMA5-15P plug of a battery charger
-The back-up power will be provided from an inverter. A 15 A power cord (1, Fig 1) with a 15
A, NEMA5-15P plug (2, Fig. 1) has been provided. This allows very convenient connection to
the 15 A, NEMA5-15R receptacle provided on the inverter. The maximum power of the back
up inverter should be less than 1800 VA as the maximum capacity of the cord provided for the
inverter connection is only 15 A.
Preset conguration - Detailed information (Please see Fig. 1, 2 and 4)
ON LED1 TERMINALS:
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
T5
T7 T8
T1 T2
T3
15 A
FUSE
BATTERY
SIDE FUSE
FOR
INVERTER
BATTERY SIDE FUSE FOR
BATTERY CHARGER
INPUT FROM INVERTER
TO NORMALLY CLOSED (NC)
CONTACT TERMINALS T5,T6
OUTPUT TO
AC BREAKER
PANEL
DISCONNECT
THE CONVERTER
EXISITING ON-BOARD
CONVERTER
30 A MAIN
BREAKER PANEL
INPUT FROM
ELECTRIC UTILITY / SHORE
POWER CORD OR GENERATOR
TO NORMALLY OPEN (NO)
CONTACT TERMINALS T3,T4
30
MAIN
BRANCH CIRCUITS
CONVERTER
12 3 4 5
BATTERY
CHARGER
BATTERY
–
+
–
+
INVERTER
–
+
–
+
T4
T6
SW1
TO BATTERY
–
+
DUAL 15 A
NEMA5-15R
RECEPTACLE
Fig.4. 30 A System for alternate source / inverter.
NOTE: In case the full 30 A, 3600 VA capacity of inverter is required to be
used, the existing 15 A cord should be replaced with a 30 A cord

9
3
INSTALLATION
a. Feed the 3 core cable from the electric utility / shore power cord / the generator through the
¾” cable clamp that has been provided (4, Fig1). Connect the three cores as follows (Fig 4):
-The black core to the black piece of wire connected to the NO, Line “L1” contact terminal
T3. Use the twist-on type of wire nut provided for splicing the ends.
-The white core to the white piece of wire connected to the NO, Neutral “N1” contact
terminal T4. Use the twist-on type of wire nut provided for splicing the ends.
-The green grounding core to one of the spare grounding studs. Use an appropriate
insulated ring or spade lug for making this connection
b. Feed the 3 core cable for output to the main breaker panel by using a convenient knockout
/ cable clamp (3/4” or 1”) for the cable entry. Cable clamp has not been provided for this
connection and has to be provided by the user. Connect the 3 cores as follows (Fig 4):
-The black core to the common Line “L” contact terminal T1 and the white core to the
common Neutral “N” contact terminal T2. Use appropriate insulated ring / fork lugs at the
bare end of the wires for rm contact.
-The green grounding core to one of the spare grounding studs. Use an appropriate ring
or spade lug for making this connection
c. Plug the NEMA5-15 plug (2, Fig 1) of the inverter power cord (1, Fig 1) to the output of
the inverter (Fig 4). Please ensure that the inverter is switched off and the battery input
connection to the inverter is disconnected.
d. Plug the external battery charger to one of the receptacles of the dual NEMA5-15R receptacle
(3, Fig 1; Fig 4). Please ensure that the AC input current of the battery charger is less than 12
A continuous as the receptacle is internally fused at 15 A max. In case the current drawn by
the external battery charger is > 12 A continuous, the charger should be wired to a separate
circuit connected to the NO contact terminals T3 and T4 through a fuse applicable to the
input current of the charger.
e. In case the Transfer Switch is being used in an RV application, the built-in converter of the RV
should be disconnected from the AC Breaker Panel (Fig 4). This is necessary because when the
electric utility / shore power cord / the generator fails / is removed, the panel will be fed by
the inverter and if the converter is not disconnected from the panel, it will result in a battery
to inverter to converter to battery loop that will quickly drain the batteries. In case the
external battery charger is not being used, the converter may be re-wired to the one of the
dual NEMA5-15R receptacles (3. Fig 1). As these receptacles are connected to the NO contact
terminals T3 and T4, the converter will always be powered from the electric utility / shore
power cord / the generator. In case the current drawn by the converter is > 12 A continuous,
the converter should be wired to a separate circuit connected to the NO contact terminals T3
and T4 through a fuse applicable to the input current of the converter.
f. In case the primary power source is electric utility / shore power cord, the time delay of 20 sec
has to be disabled by setting the internal DIP Switch SW1 (Figs 2, 4) to ON position. In case the
primary source is generator, the internal DIP Switch SW1 (Fig 2, 4) should be retained in the
preset off condition (1) .

10
3
INSTALLATION
Testing of the operation (Fig 4)
READ AND FOLLOW ALL SAFETY INSTRUCTIONS BEFORE TESTING THE
OPERATION
a. Plug in the power cord. As the time delay has been disabled (As explained above, if the
primary source is electric utility / shore power cord, the time delay should be disabled by
changing the position of the DIP Switch SW1 to ON position), the relay coil will energize as
soon as the power cord is plugged in. The green LED1 will light up indicating that the relay
has energized. If the main panel circuit breakers are switched on, the RV loads should operate
normally. The external battery charger will start charging the batteries.
b. Switch on the inverter. The inverter will be in standby condition.
c. Unplug the power cord. The relay will immediately de-energize and the AC loads will be
transferred to the inverter.
Installation between Power Cord and Generator (Fig 5)
This conguration is used in RV application when it is desired to switch between the shore power
cord and the onboard generator. When the load demand in the RV is more than the capacity of the
Shore Power Cord / the breaker capacity of the RV Park / Camp Ground, the on-board generator
is required to be started. In this case, the AC loads should transfer to the generator as soon as the
generator is started and is ready to take on the load (after a delay of around 20 to 25 sec).
ON LED1 TERMINALS:
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
T5
T7 T8
T1 T2
T3
15 A
FUSE
INPUT FROM SHORE POWER CORD
TO NORMALLY CLOSED (NC)
CONTACT TERMINALS T5,T6
OUTPUT TO
AC BREAKER
PANEL
INPUT FROM GENERATOR
TO NORMALLY OPEN (NO)
CONTACT TERMINALS T3,T4
30 A MAIN
BREAKER PANEL
30
MAIN
BRANCH CIRCUITS
12 3 4 5
T4
T6
SW1
PCB1
Fig.5. Typical Generator / power cord.