02-18-2014, 07:16 AM
(This post was last modified: 02-18-2014, 07:25 AM by Hopefuldave.)
I like ABB manuals, translated from the Nordic to English by someone who speaks BOTH languages well!
Mine's set up for 10, 25 and 50Hz fixed speeds on a switch (bit of diode matrix to get the right inputs) and 5-80Hz variable, the big BTH motor in the Holbrook's balanced well enough to stand a 2p coin on edge at 80Hz / 2500 spindle rpm full chat (with nowt in the collet) but I've wired a relay to one of the VFD outputs for an additional 240v cooling fan to switch off above 40Hz, as at low speed the fan won't push enough air to keep it cool... Wiring it that way (using the normally closed contacts, active 'above supervisory frequency' in ABB lingo) means the fan runs when stopped / VFD powered-off too, so it cools off between operations unless I isolate the machine.
Most VFDs have a few relay outputs and parameters to select what they mean, another one switches the suds VFD on and off with the motor, that's very handy! There are usually lots of meanings you can assign to the input (control) terminals too, fixed speeds, jog input, different motor.parameter etc., and more than enough for acceleration/deceleration rates, flying start (useful on a multi-speed motor), v/f curves etc - I was a bit daunted by the ABB book, and that's in GOOD English!
When setting up there's a parameter for nominal frequency, this is the point where the full line voltage is applied and it goes constant-hp - you can set it anywhere in the range, but too low and you'll risk over-current in the motor, as the back-emf is proportional to supply frequency - don't go below 45-50Hz on a 60Hz motor or you could cook it!
Mine's set up for 10, 25 and 50Hz fixed speeds on a switch (bit of diode matrix to get the right inputs) and 5-80Hz variable, the big BTH motor in the Holbrook's balanced well enough to stand a 2p coin on edge at 80Hz / 2500 spindle rpm full chat (with nowt in the collet) but I've wired a relay to one of the VFD outputs for an additional 240v cooling fan to switch off above 40Hz, as at low speed the fan won't push enough air to keep it cool... Wiring it that way (using the normally closed contacts, active 'above supervisory frequency' in ABB lingo) means the fan runs when stopped / VFD powered-off too, so it cools off between operations unless I isolate the machine.
Most VFDs have a few relay outputs and parameters to select what they mean, another one switches the suds VFD on and off with the motor, that's very handy! There are usually lots of meanings you can assign to the input (control) terminals too, fixed speeds, jog input, different motor.parameter etc., and more than enough for acceleration/deceleration rates, flying start (useful on a multi-speed motor), v/f curves etc - I was a bit daunted by the ABB book, and that's in GOOD English!
When setting up there's a parameter for nominal frequency, this is the point where the full line voltage is applied and it goes constant-hp - you can set it anywhere in the range, but too low and you'll risk over-current in the motor, as the back-emf is proportional to supply frequency - don't go below 45-50Hz on a 60Hz motor or you could cook it!
Rules are for the obedience of fools, and the guidance of wise men...
(Douglas Bader)
(Douglas Bader)