For frame size 07 drives and larger, which use a d.c. link charge system based on a half controlled thyristor input bridge, the rate at which the d.c. bus is

charged can be reduced by setting Slow Rectifier Charge Rate Enable (06.071) to one. This will reduce the charging current which may be required if

significant additional capacitance is added to the d.c. link to prevent rupturing of input fuses.

Parameter

06.072 User Supply Select

Short description

Set to 1 to select the supply from the user 24V input

Mode

Open‑Loop

Minimum

Default

Type

1 Bit User Save

Display Format

Standard

Coding

The power for the drive control system is either taken from the user 24V power supply or the main supply (i.e. derived from the power circuit d.c. link). If

Low Under Voltage Threshold Select (06.067) = 0 and Backup Supply Mode Enable (06.068) = 0 and User Supply Select (06.072) = 0 then the

supply used is determined as follows for drive sizes 5 and below. (For drive sizes 6 and above a diode OR system is used to select the required power

supply, and so this is done automatically in hardware.)

1. When the drive first powers up it tries to use the main supply or the user 24V supply in turn until the drive starts up, begining with the main supply.

2. If the main supply is active and the d.c. link voltage (D.c. Bus Voltage (05.005)) falls to a level where it is no longer possible to communicate with

the power stage then the drive attempts to switch over to the user 24V supply. If the user 24V supply is not present then the drive will power

down, otherwise it will continue to run off the user 24V supply. The level at which the power stage powers down depends on whether the user 24V

supply is present or not. However this is maybe below half the minimum for Standard Under Voltage Threshold (06.065) depending on the drive

power supply loading from option modules, encoders, I/O etc..

3. If the user 24V supply is being used and the d.c. link voltage (D.c. Bus Voltage (05.005)) rises above 95% of the minimum for

Standard Under Voltage Threshold (06.065) then the drive attempts to switch to the main supply.

The following should be noted:

1. Parameters can be saved by setting Parameter mm.000 (mm.000) to 1000 (not in under-voltage state), or to 1 or 1001 (in any state) and initiating

a drive reset. Power-down save parameters are saved when the under-voltage state becomes active.

2. If the drive is powered from the user 24V supply and then the main supply is activated but is not above 95% of the minimum for

Standard Under Voltage Threshold (06.065) then the drive will continue to be powered from the user 24V supply. If the user 24V supply is

subsequently removed the drive will power down, but then if the main supply is high enough will power up again on the main supply.

3. Although the drive can run off power derived from its d.c. link at a level well below the minimum for Standard Under Voltage Threshold

(06.065) the level down to which it will operate depends on the loading applied by option modules, position feedback devices and I/O. For reliable

operation it is advisable that the d.c. link voltage is above 90% of the minimum for Standard Under Voltage Threshold (06.065) when the 24V

supply is not present.

4. It is possible to initiate saving power-down save parameters by forcing the drive into the under-voltage state by

changing Low Under Voltage Threshold Select (06.067) from 1 to 0 when the d.c. link voltage is below 90% of the minimum of

Standard Under Voltage Threshold (06.065). This is not advisable because failure of the 24V supply or the main supply at this point could result in

corruption of the drive parameters saved in non-volatile memory.

If Low Under Voltage Threshold Select (06.067) = 1 or Backup Supply Mode Enable (06.068) = 1 or User Supply Select (06.072) = 1 then the 24V user

supply is always selected. If the user 24V supply is not present then a User 24V is initiated. The following should be noted:

1. The drive will still power-up on the main supply even if the user 24V supply is not present because the drive tries each supply in turn to power up,

however the drive will remain in the tripped state until the user 24V supply is activated.

2. Parameters can only be saved by setting Parameter mm.000 (mm.000) to1001 and initiating a drive reset. Power-down save parameters are not

saved when the under-voltage state becomes active.

Parameter

06.073 Braking IGBT Lower Threshold

Short description

Defines the lowest level of the d.c. bus voltage where the braking IGBT becomes active

Mode

Open‑Loop

Minimum

−VM_DC_VOLTAGE_SET

Default