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 configured 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
rectified 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
