How your ACS355 protects itself

When your ACS355 displays a fault, don’t just get frustrated, a large proportion of the time it’s just asking you to make sure the environment’s correct, so you don’t end up with a melted chunk of plastic instead of an advanced control device.

Many these drives are installed in rural areas as solar pump controllers, so this will also cover some common solutions to save on driving way out there.

Below is the link to the ACS355 manual if you want to follow along with the parameters.

ACS355 Manual

Parameter group 30 is where the fault functions are found, so now we’ll go through them in order:

This parameter allows you to set a fault trigger when your analogue reference you use to control the drive falls below a set value. Most of the rural pump station won’t use this, but it’s handy to have if you’re doing some more control. By default, this fault is disabled, but can be set to either fault the drive, run at a constant speed or run at the last speed of the drive.

This one is straightforward; the drive will fault is the keypad attached to the front is removed. This one can be change so that the drive will run at a constant speed or the last used speed instead. If you’re using this drive in a simple run or don’t run scenario this one can be worth setting to CONST SP 7(2) or LAST SPEED (3) since you don’t want a break in the connection to mean a 4 hour drive to reset it. Just remember if you set CONST SP 7 you need to define the speed/frequency you want it to run at in parameter 12.08.

30.03 and 30.04:
These two are the same thing, just allowing for two different inputs. These allow you to trigger a fault manually using an available digital input on the drive. Usually you aren’t going to want more ways to make the drive stop, but this can be handy if you have it connected to something else that might fail such as a controller. Connect them up and if the digital signal goes down the drive will fault.

30.05 through 30.09:
These parameters deal with motor overtemperature protection. Now by default the drive doesn’t have any actual temperature sensors connected, however using the motor parameters set here we can define a model for our motor and allow the drive to estimate the motor temperature. This is a little bit advanced so we won’t cover it here, the main one to know is 30.05, by default this will trip when the motor is over temperature with error 0009. If you’re in a scenario where you don’t have a sensor connected and you’re sure the motor isn’t overheating there may be an issue with the model. You can turn off this fault, however it is not recommended.

30.10 through 30.12:
These define the stall protection for the motor. By default this is off and generally you’ll leave it that way unless you need it. This defines how the unit responds in the case of a motor stall (shaft can no longer turn). The options here are NOT SEL, FAULT and ALARM.

30.13, 30.14 and 30.15:
This allows you to set the drive to fault or alarm if the torque load is determined to be low. Not usually required, but can be useful. Fourteen allows you to set the timeout to determine underload. Fifteen allow you to define the torque load curve for underload detection.

This one is important and by default faults the drive bringing it to a stop. This one triggers on significant ripple on the DC bus voltage. The typical causes of this are a lost phase to the drive or other interruptions to the supply. Disabling this can cause damage to the drive if it continues to operate while the power is unreliable. If the drive is in a remote area with regular minor fluctuations and resetting the fault takes some time you can set this to LIMIT/ALARM which will not fault the drive but will limit the output current. If you are certain they fluctuations are only very short you can set this to ALARM only.

This is a big one. This one will cause the drive to the shut down in the even it detects a short to earth in the motor or motor cable. There is the option to disable this one however it is not recommended in any scenario to do so. Disabling this fault warning will generally void the warranty on the unit.

30.18 and 30.19:
This defines the response from the drive in the case of a loss of comm controls as well as the timeout delay. This one’s simple, what do you want the drive to do if it loses the controller. Your options are fault, constant speed, last speed or no response.

30.21 and 30.22:
This one is only useful if you are using analogue inputs. These control the response to a low value from AI1 and AI2.

This fault triggers when incorrect wiring is detected, i.e. wiring input power into the motor terminals. There is no reason to ever disable this and doing so may void your warranty.

STO operation controls what happens when the safe torque off function of the drive is triggered. Primarily going to be used in fault mode.

This controls how the drive responds when some tries to start the motor when the drive only has control circuitry powered through the MPOW-01 auxiliary power module. The motor cannot run, but you can set for a fault, alarm or no indication.

This one controls whether the drive trips when it loses comms with an expansion module, such as a MREL-01.

This selects whether the drive that faults coasts to a stop or follows an emergency ramp function. Regardless of this parameter the drive will coast to a stop on the following faults:
  • 0002 DC OVERVOLT
  • 0004 SHORT CIRC
  • 0045 STO1 LOST
  • 0046 STO2 LOST

That covers the list of fault options and some general solutions. Hopefully this saves you a trip to the outback.