Auto Phase Sequence Corrector
If the grid drops a phase or your electrician swaps R-Y-B, your three-phase motor will reverse, overheat, or burn. The PSC detects wrong-sequence within milliseconds and either auto-corrects or shuts off.
The DISCOM linesman was doing maintenance on the line feeding your pump house. When he reconnected the cable, he swapped two phases. Your three-phase pump motor started, in reverse. The Subtech PSC prevents it.
What is a Phase Sequence Corrector?
A three-phase motor's direction of rotation is determined by the order in which the three phases arrive at its terminals. If even one pair of phases is swapped, the motor runs backward.
A pump motor running in reverse is not just inefficient. It actively damages itself and the system. The impeller runs backward, creating cavitation.
Phase sequence errors happen more often than people realise. The DISCOM linesman swaps two phases during line maintenance. A contractor wires the incoming cable with R and B transposed.
The Subtech PSC 33 monitors the incoming three-phase supply continuously. When the sequence is wrong, it detects this within 50 milliseconds and either automatically swaps two phases internally (auto-correct mode) or opens the contactor (trip mode).
The PSC 33 also includes phase failure protection. If any one of the three phases is absent, the unit trips the motor immediately.
Why this matters for your facility
Phase Sequence Detected in Under 50 Milliseconds.
Before the motor has had time to start rotating in the wrong direction, the PSC has already detected the error and either corrected or tripped.
Auto-Correct Mode: Wrong Sequence Fixed Automatically.
In auto-correct mode, the PSC internally swaps two phases to restore the correct R-Y-B sequence before passing power to the motor.
Trip Mode: Wrong Sequence Shuts the Motor Off.
In trip mode, the PSC opens the contactor and shuts off power if the phase sequence is wrong.
Phase Failure Protection Included.
If any one phase is absent, the PSC trips the motor within 50ms.
PMC Contactor: 5-Year Coil Warranty.
The PSC 33 uses Subtech's PMC (Permanent Magnet Contactor) as the switching element.
Simple Field Installation. No Configuration Software.
The PSC 33 is a plug-in device: incoming three-phase cable in, outgoing cable to motor out.
Where Subtech panels are deployed
Pump Houses on Rural Grid
Rural DISCOM feeders are frequently switched and reconnected by linemen without consistent phase marking.
CNC Workshops and Machining Centres
A CNC machine spindle running in reverse will cut backward and scrap the workpiece.
Lift and Elevator Motor Control
An elevator motor running in reverse when the controller commands up-travel is a serious safety fault.
Food Processing where Reversed Motor Scraps the Batch
Mixer, conveyor, and filling machine motors running in reverse scrap the product batch.
Agriculture Irrigation Pumps
Borewell and surface pump motors on agricultural connections are frequently reconnected by local electricians without phase sequence instruments.
Air Compressors and Refrigeration Compressors
Compressor motors running in reverse build no pressure and trip on high discharge temperature.
PSC Model Range
All PSC models include phase failure protection and choice of auto-correct or trip mode.
PSC 33
Standard model. Detects and corrects or trips on wrong phase sequence and phase failure within 50ms.
Get quotePSC 100
Higher current rating for larger three-phase motors and incomer protection applications.
Get quotePSC + ACCL Combined Module
Combines phase sequence correction with ACCL current limiting in a single panel.
Get quoteTechnical Specifications: PSC 33
| Operating Voltage | 380-440V AC, three-phase |
| Current Capacity | 63A (PSC 33); 100A (PSC 100) |
| Detection Time | <50 ms from power-on |
| Phase Failure | Trips within 50ms on loss of any phase |
| Switching Element | Subtech PMC Contactor (5-year coil warranty) |
| Modes | Auto-correct and Trip (front-panel switch selectable) |
| Enclosure | CRCA steel, powder-coated, wall-mount |
| Operating Temperature | -10°C to 55°C |
Why Subtech PSC
Sub-50ms Detection. Faster Than a Motor Can Start.
A three-phase motor takes 100-500ms to reach starting speed from rest. Our 50ms detection ensures the PSC has already acted before the motor starts rotating.
PMC Contactor with 5-Year Coil Warranty
The contactor in the PSC 33 is Subtech's own PMC, the industry's only 5-year coil warranty product.
Auto-Correct Mode: No Site Visit After Line Work
In auto-correct mode, the PSC corrects phase sequence without human intervention.
25 Years of Motor Protection
Subtech has built motor protection panels for water utilities, PSUs, and industrial plants since 1998.
220+ Dealers Pan-India
Available through 220+ Subtech dealers in 28 states.
Frequently asked questions
What is phase sequence and why does it matter for a three-phase motor?
How does the PSC 33 auto-correct the phase sequence?
Should I use auto-correct mode or trip mode?
Does the PSC 33 protect against single-phasing (loss of one phase)?
Ready to spec your phase sequence corrector?
Share your single-line diagram, load list or three months of electricity bills. Our engineers will respond with a custom BOM, quote and delivery schedule within 24 hours.