rpoet
Member
Hi All,
I have a portable power distro that serves power to up to eight Parker Gemini servo systems. These controllers are most happy running on three-phase 208v power, but are also able to be used on 240v single phase, with reduced capabilities. We will mostly be using the distro on three-phase power, but there may be times when we need to use single phase.
We can account for the reduced capabilities of the servos on single phase if we plan for it, but it would be a problem if we drop a leg (and it has happened here) and we didn't know it; the servos will run but will not be able to generate the torque necessary for some applications. The easy solution is a phase-monitor relay, but I've only found these available for three-phase applications.
Since there may be call for running from single- phase, I'm leaning towards three relays, each with coils wired between two phases to sense a dropped leg. The N.O. contacts would be wired to the PLC and tell it to drop the power contactors to the drives until the situation is fixed. I'll add a selector switch to the PLC to let it ignore the third relay if we're running on single-phase power.
Alternatively, I'd entertain a dedicated phase-loss / power quality relay that can be set for either single phase or three phase input with a selector switch. I just haven't found it if that critter exists. Any thoughts would be appreciated.
-rpoet
I have a portable power distro that serves power to up to eight Parker Gemini servo systems. These controllers are most happy running on three-phase 208v power, but are also able to be used on 240v single phase, with reduced capabilities. We will mostly be using the distro on three-phase power, but there may be times when we need to use single phase.
We can account for the reduced capabilities of the servos on single phase if we plan for it, but it would be a problem if we drop a leg (and it has happened here) and we didn't know it; the servos will run but will not be able to generate the torque necessary for some applications. The easy solution is a phase-monitor relay, but I've only found these available for three-phase applications.
Since there may be call for running from single- phase, I'm leaning towards three relays, each with coils wired between two phases to sense a dropped leg. The N.O. contacts would be wired to the PLC and tell it to drop the power contactors to the drives until the situation is fixed. I'll add a selector switch to the PLC to let it ignore the third relay if we're running on single-phase power.
Alternatively, I'd entertain a dedicated phase-loss / power quality relay that can be set for either single phase or three phase input with a selector switch. I just haven't found it if that critter exists. Any thoughts would be appreciated.
-rpoet