Hi,

I am new to this forum, so please go easy on me... :)

I have the following:

Water pump application, with CN009 and AP010 configured and...

Australia, so 50Hz power.

• p1082 = 50Hz
• p1080 = 15Hz
• p2292 = 30%
  
• p2365 = 1
• p2366 = 5
• p2367 = 2
• P2258 = 5
• P2257 = 5
• P2293 = 6
  
  

I use the Hibernation mode to shut the pump off if at high pressure (15Hz) for > 5 seconds.

It works well except for the ramp-up time from 15 Hz to 50 Hz from a low-pressure situation. 

In a simulation using a potentiometer instead of the pressure sender, I turn the "pressure" up to 10 Bar. The VFD ramps down from 50Hz to 15Hz quite fast. I wait for Hibernation to kick in (5 seconds). The VFD then ramps down to 0 Hz gracefully. I then turn the Pot to simulate 1 Bar. The VFD ramps from 0Hz to 15Hz slowly then goes from 15Hz to 50Hz really fast.  The pump does not like that at all...

Any tips or advice for a newbie?

**Sorry about the .zip file attachment. This forum does not support MP3 :/..

Hello,

If you choosen CN009 did you trigger one of these inputs (DI2 or DI3 or DI4) like manual you should trigger it to choose fixed setpoint.To work like PID reguliator. Also check or actual value sensor connected to AI2  or it's configured like (4-20mA)

If you don't need controlling like PID maybe you can use CN002 then configure parametres and maybe it will work see manual:

Hi Gents,

Thanks for your answers.  Let me give some additional context...

As the V20 does not do 4-20ma natively, I changed to using a 0-10V input on AI2.  From the pressure sender, I added a resistor to convert the 4-20ma to 2-10v. I configured p0756[1] = 0 to read the voltage. The V20 is reading the voltage correctly. r0752[1] shows the correct voltage at different pressures.  I swapped the sensor input out to a potentiometer to simulate this voltage input (2-10v) whilst chasing this issue.  Again - this works well, as r0752[1] reports the correct voltage values. The PID reacts to the changes quite well. It's just the hibernation function that causes the drama.

Going back to first principles, all I need is for the VFD to control my variable-speed water pump to a constant pressure. it does need to turn the pump off when the pressure is at the max limit rather than running constantly at 15 Hz.  This is what I used the Hibernation mode for. Without hibernation, the PID spools the pump up and down perfectly, it just does not turn the pump off.  It's with hibernate function on that the pump goes from 15Hz to 50Hz way too fast.

In my mind, I hear 3 things, time from hibernate (ENABLE = OFF) to run mode (ENABLE = ON), time from run mode until the drive is actually able to spin up a motor (it takes some time for the drive to being to provide pulses at the output), and the ramp up rate.

The timing is tricky if the current drive's state is not fully monitored.

For example, without knowing the drive is actually ready to enable pulses and sending a speed setpoint and enable on will cause a kind of jump start in some drives - which sounds like what you are experiencing.

If however the drive state that it is not yet ready to move the motor is used to force a 0 speed setpoint, no jump start should happen.  And, if a suitable ramp up rate is established, it should smoothly ramp up to speed once the drive ready signal is received and a speed setpoint is then sent to the drive.

That said, you can - if using a PLC - provide a ramped speed setpoint via PLC logic.  Also, there are physical devices that can provide a ramp up signal upon a digital input state change to an established level (setpoint in your case).

jmalan69

Hi Gents,

Thanks for your answers.  Let me give some additional context...

As the V20 does not do 4-20ma natively, I changed to using a 0-10V input on AI2.  From the pressure sender, I added a resistor to convert the 4-20ma to 2-10v. I configured p0756[1] = 0 to read the voltage. The V20 is reading the voltage correctly. r0752[1] shows the correct voltage at different pressures.  I swapped the sensor input out to a potentiometer to simulate this voltage input (2-10v) whilst chasing this issue.  Again - this works well, as r0752[1] reports the correct voltage values. The PID reacts to the changes quite well. It's just the hibernation function that causes the drama.

Going back to first principles, all I need is for the VFD to control my variable-speed water pump to a constant pressure. it does need to turn the pump off when the pressure is at the max limit rather than running constantly at 15 Hz.  This is what I used the Hibernation mode for. Without hibernation, the PID spools the pump up and down perfectly, it just does not turn the pump off.  It's with hibernate function on that the pump goes from 15Hz to 50Hz way too fast.