.png)
Selfguard's Automatic Star Delta Control Panel (SDP) is specifically built for three-phase motors and provides a very dependable technique of starting big motors by lowering electrical stress and protecting against major defects.
What Is the Selfguard Automatic Star-Delta Control Panel?
- The SDP panel can support motors from 20 HP to 75 HP, and the overload relay ranges from 10-45 Amps to 65-120 Amps depending on the type.
- It is completely automated, with contactors and digital timers controlling the seamless and safe transition from star to delta connection.
- The panel includes microcontroller technology, which ensures modern, accurate control.
Key Features & Protections
According to Selfguard’s own description, the SDP panel includes:
- Digital voltmeter and ammeter, with an inbuilt overload relay
- Short-circuit protection
- Protection from reverse phasing and running on two phases
- Protection from voltage imbalance among phases
- Built-in delay timers for three things: three-phase sensing, star position, and delta position
- Indicators for:
- Reverse phase, missing phase, and correct phase sequence
- Star position and delta position during motor operation
How the Panel Works: Operating Modes
Selfguard explains the working procedure of this panel in two modes: manual and automatic.
- Manual Mode:
- Pressing the Green (Start) button starts the motor in the star position.
- Then, pressing the Yellow (Run) button moves it into the delta position.
- Pressing the red (Stop) button stops the motor.
- In this mode, the Single Phasing Preventer (Auto Switch) does not operate
- Auto Mode:
- The Auto Switch first checks for the existence of all three phases in the proper sequence
- When correct, a green indicator lights up and the panel starts in star position
- After the timer's specified delay, the panel automatically shifts to the delta position
- In either mode, the star and delta indicators light up properly, and the overload relay works
Overload Relay Functionality
- After pressing the "Panel On" button, the overload relay panel displays the current "tripping" amperage for two seconds
- This tripping current can be changed using a knob at the back of the overload relay, depending on the motor's rated current
- If the motor's current exceeds the set tripping value, the panel will stop the motor after a built-in delay and display "OL" (overload)
Single Phasing Preventer / Auto Switch
- If the three phases are in the right order, after a predetermined interval, a green lamp shines to indicate, and the Auto Switch begins
- Incorrect sequences cause the red indicator to flicker
- If any phase is absent, the red lamp will glow continually
Voltage Monitoring
- A voltage selector switch is provided on the front panel to view phase-to-phase voltages: RY, YB, or BR.
Why This Panel Is Essential for Heavy Motors
- The automatic star-delta device lowers inrush current and stress during motor startup. This is especially useful for big three-phase motors
- Built-in safeguards (reverse phasing, single phasing, and imbalance) guarantee motor safety and longevity
- The adjustable overload relay helps match protection precisely to the motor's rated current
- Clear indication lamps (phase status, star/delta, and overload) make diagnosis and control simple
Panel Range & Application
- Selfguard sells this panel for motors ranging from 20 HP to 75 HP
- This makes it suited for a wide range of three-phase motor applications in the industrial, agricultural, and commercial sectors
Conclusion
The Selfguard Automatic Star Delta Control Panel provides a dependable and efficient method to operate heavy three-phase motors. With automatic star-to-delta shifting, built-in protection features, overload control, and clear visual indicators, it ensures smoother motor starting, reduced electrical stress, and enhanced safety. Its combination of microcontroller-based precision and protection mechanisms makes it an essential solution for any environment where heavy motors need reliable and controlled operation.