Phases Sequence Monitor
We design this phases sequence monitor to protect three phases' loads, sensitive to phase's sequence from wrong phase's sequence, phase missing, overvoltage, undervoltage and phases unbalance. We use singlechip microcontroller from PIC12C family of MICROCHIP and there are designed four main versions with few different modifications. The version with one relay output 10A/240 VAC has usual power supply, every other - with one or two output optrons and with output triac are with transformerless power supply, direct connected to T phase. The modifications are based on two different user programmes and the possibility to choice positive or negative working logic. The response time after phase missing or other event is software programmable and is in the range 0,06 - 2,55 s.
TECHNICAL SPECIFICATIONS
| PHSM-O1 | PHSM-O2 | PHSM-T | PHSM-R | ||
|---|---|---|---|---|---|
| Supply voltage | V | 220, 50Hz | 220, 50Hz | 220, 50Hz | 220, 50Hz |
| Power consumption | VA | 0,2 | 0,25 | 0,25 | 1,35 |
| Response time | s | 0,06 - 2,55 | 0,06 - 2,55 | 0,06 - 2,55 | 0,06 - 2,55 |
| Initial settle time | s | < 1 | < 1 | < 1 | < 1 |
| Overvoltage level | V | 255 | 255 | 255 | 255 |
| Undervoltage level | V | 175 | 175 | 175 | 175 |
| Level accuracy | % | 5 | 5 | 5 | 5 |
| Output current and voltage | A; V | 0,03/32 DC | 0,03/32 DC | 10/220 AC | 4/420 AC |
The action of the phase's sequence monitor is the next: after switching on the supply voltage the output settles in a "switch off" state. For 20 ms it tests the presence, the sequence and the voltage level of all three phases. If everything is OK, the output settles in a "switch on" state. By event (for example overvoltage or phase missing) the output settles in a "switch off" state. The repetitive switch on the unit is made after restoring the normal parameters of the power line.
The phase's sequence monitor offers in a plastic's case with overall dimensions 86x70x58 mm with clamp for mounting on a Eurobus. The electric mounting is made by clamps, parallel to the three phases and "zero". It is suitable for protection of sequence sensitive loads like motors or specialized power supplies, by event PLC controlled.