Protections And Alerts; Speed-Drop Protection Mode - Emerson EV3 Series Application Manuallines

6

Protections and alerts

When the drive is in normal operation, the power LED will always be turned on and the fault LED will
be off. In case the drive is in fault or protection mode, the fault LED will flash at 2 Hz for a specific
number of times. The frequency of the LED flashing is linked to one of the alarm codes shown in
Table 20.
6.1

Speed-Drop Protection mode

To protect the drive in case of overcurrent or overtemperature, the drive will take over the speed
control to reduce the component stress by decreasing the speed.
Four different speed-drop protection levels can be used and are shown below:
Figure 12: Speed-Drop Protection logic
▪ Immediate shutdown
o
The compressor will be shut down
▪ Speed-Drop Protection
o
The compressor speed will drop by 200 rpm/s
▪ Speed Holding
o
The compressor speed will be kept constant
▪ Speed-Drop Protection Recovery Limit
o
Undercut this limit the drive will recover and will give back the speed control to the controller.
Going upwards the speed-drop protection axis:
If the current/temperature value exceeds the speed drop protection limit, the drive will take over the
speed control.
If Active Envelope Control is used, the drive can foldback the speed of the compressor to the
minimum speed of the sub-region in which it operates (stored and frequently updated depending on
the region, in registers [44] and [109]).
If running in Full Envelope Control mode, the foldback speed will be the minimum allowed
compressor speed valid for the whole envelope (stored in register [109]). An immediate shutdown
will occur if the Maximum Allowed Values limit is exceeded.
Going downwards the speed-drop protection axis:
If the current/temperature value during the Speed-Drop Protection mode reaches the foldback speed
it will stay at that level. In case of additional speed reduction need, the drive will stop the compressor
after 30 seconds and a timeout fault will be triggered in registers [79] and [81].
If the current/temperature value decreases into the speed holding area, the compressor speed will
be kept constant, at the value at which it was running when the speed-drop protection limit was
crossed.
If the current/temperature value is between the speed holding limit and recovery limit the following
control method is used:
▪ The compressor will run at reduced speed.
▪ The controller partially gets back the control (only allowed to decrease the speed in this area).
▪ If possible the controller should adjust the system parameters to come below the recovery limit!
▪ Once the recovery limit is undercut or the compressor runs at this stage for longer than
30 seconds, the system controller will get back the full speed control.
NOTE: The drive will inform the controller by updating Modbus registers [5] and [51].
20 AGL_Sol_EV3_E_Rev_01