Emerson E300 Series Design Manual page 86

Safety Product Mechanical
information information installation
Going from low voltage operation to normal mains operation requires the inrush current to be controlled. This may be provided externally. If not, the
drive supply can be interrupted to utilize the normal soft starting method in the drive. To fully exploit the new low voltage mode of operation the under
voltage trip level is now user programmable. Details of the drive set-up and operating parameters are given below.
Table 4-12 Low voltage operation parameters
Parameter Description
O09 Active Supply
O10 User Supply Select
O11 Standard Under Voltage Threshold
O12 Low Voltage Supply Mode Enable
O13 Low Under Voltage Threshold Select
O14 Low Under Voltage Threshold
O15 Under Voltage System Contactor Output
O16 Under Voltage System Contactor Closed
Active Supply
Parameter Active Supply (O09). If LV Supply Mode Enable (O12) = Off (0) then Active Supply (O09) = Off (0). If LV Supply Mode Enable (O12) = On
(1) then Active Supply (O09) = Off (0) when the DC link voltage is above the upper under-voltage threshold otherwise Active Supply (O09) = On (1).
User Supply Select
Parameter User Supply Select (O10). The power for the drive control system is either taken from the user 24 V power supply input or it is derived
from the DC link. If Low Under Voltage Threshold Select (O13) = Off (0) and LV Supply Mode Enable (O12) = Off (0) and User Supply Select (O10) =
Off (0) then the supply used is determined from the level of the DC Bus Voltage (J65). A hysteresis band is provided: if DC Bus Voltage (J65) is less
than 85 % of the minimum value for Standard Under Voltage Threshold (O11), the 24 V user supply is selected, if DC Bus Voltage (J65) is more than
95 % of the minimum value for Standard Under Voltage Threshold (O11), the main supply is selected. If the user 24 V supply is not present and DC
Bus Voltage (J65) is less than 85 % of the minimum value for Standard Under Voltage Threshold (O11) then the drive simply powers down.
Parameters can be saved by setting Pr mm00 to 1 or 1000 (not in under-voltage state) or 1001 and initiating a drive reset. Power-down save
parameters are saved when the under-voltage state becomes active.
If Low Under Voltage Threshold Select (O13) = On (1) or LV Supply Mode Enable (O12) = On (1) or User Supply Select (O10) = On (1) then the 24 V
user supply is always selected if present. If the user 24 V supply is not present then it is not selected and a PSU 24V trip is initiated.
Parameters can only be saved by setting Pr mm00 to 1001 and initiating a drive reset. Power down save parameters are not saved when the under-
voltage state becomes active. It should be noted that for drive sizes 6 and below, if both the 24 V user supply and the main supply are present and the
user 24 V supply is removed, the drive will power down and then power up again using the main supply.
Standard Under Voltage Threshold, Under Voltage System
The under-voltage system controls the state of Under Voltage (L19) active which is then used by the sequencer. Each under voltage threshold
detection system includes an hysteresis of 5 % of the actual threshold level therefore:
DC link voltage
Vdc
Threshold < Vdc
Vdc > Threshold x 1.05 *
* Hysteresis is 5% subject to a minimum of 5 V
When Under Voltage (L19) = On (1) the sequencer will change and it is not possible to enable the drive. The under-voltage system operates in
different ways depending on the setting of LV Supply Mode Enable (O12). If the Low Under Voltage Threshold (O14) is used or if back-up supply
mode is selected the internal drive power supplies are normally powered from the 24 V supply input i.e. (Digital I/O 13). User Supply Select (O10)
should be set to On (1) to select this supply and its monitoring system.
Low Voltage Supply Mode Enable = Off (0)
If Low Under Voltage Threshold Select (O13) = Off (0) then the under voltage threshold is defined by Standard Under Voltage Threshold (O11). If Low
Under Voltage Threshold Select (O13) = On (1) then the under voltage threshold is defined by Low Under Voltage Threshold (O14)
Size 6 drives and smaller have a charging resistor that is in circuit for either the main AC or DC power supplies to the drive. The charge system is
generally active when Under Voltage (L19) = On (1) and inactive when Off (0).
If the DC link voltage is above the under-voltage threshold and Under Voltage (L19) = Off (0) a large surge of current can occur if the AC supply is
removed and then reapplied to the drive.
If the under voltage threshold needs to be lower than the minimum of Standard Under Voltage Threshold (O11), then the Low Under Voltage
Threshold (O14) should be used. It is important that the difference between the under-voltage threshold level and the peak of the supply voltage is
never larger than the difference between the minimum Standard Under Voltage Threshold (O11) and the peak of the maximum allowed AC supply
voltage for the drive. For example:
The minimum Standard Under Voltage Threshold (O11) for a 400 V drive is 330 V see Low Under Voltage Threshold (O14) )
Maximum allowed AC supply voltage:
Peak of maximum allowed AC supply voltage:
The difference between the under-voltage threshold and the peak supply voltage = 747 - 330 = 417 V
Therefore for this drive voltage rating the peak line to line voltage must never be higher than Low Under Voltage Threshold (O14) + 417 V.
If Low Under Voltage Threshold Select (O13) = On (1) and Low Under Voltage Threshold (O14) is reduced below the variable maximum level
VM_STD_UNDER_VOLTAGE[MIN], or LV Supply Mode Enable (O12) = On (1), an indication is stored in Potential Drive Damage Condition (L73)
86
Electrical Getting
User Menu A Commissioning
installation started
Under voltage detection
Active
No change
Not active
480 V + 10 %
480 x 1.1 x √2 = 747 V
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E300 Design Guide
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