Emerson E300 Series - Page 421

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E300 Design Guide 421
Issue Number: 1
For example:
The minimum Standard Under Voltage Threshold (O11) for a 400 V drive is 330 V
The maximum allowed supply voltage for this drive is 480 V + 10 %
The peak of the maximum allowed supply voltage = 480 x 1.1 x √2 = 747 V
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) is set to one and Low Under Voltage Threshold (O14) is reduced below the variable maximum level
VM_STD_UNDER_VOLTAGE[MIN], or if LV Supply Mode Enable (O12) is set to one, an indication is stored in Potential Drive Damage Conditions
(L73) that cannot be cleared by the user. This marks the drive, so that if it is damaged as a result of an input current surge, this can be detected by
service personnel.
For frame size 07 drives and larger, which use a d.c. link charge system based on a half controlled thyristor input bridge, the charge system is
activated based on the level of the voltage at the a.c. supply terminals of the drive. The threshold for the charge system is set so that the rectified
supply will give the required under-voltage threshold level. The under-voltage system operates in exactly the same way as for frame size 07 drives
and smaller except that the delay during the transition out of the under-voltage state is extended. For single power module drive the delay is 1.0 s to
allow the thyristor charge system to charge the d.c. link. For parallel power modules the delay is extended to 2.5 s to ensure that all modules power
up correctly.
Figure 8-36 Backup Supply
Vdc
Soft-start active
Under
-
voltage
Active (L19)
Under
-
voltage threshold
Under
-voltage threshold x 1.05
Under-voltage timing with Back-up Supply Mode Enable (O12) = 1
(Frame sizes 08 and larger)
Under-voltage Active (L19) cannot be zero until Under-
voltage System Contactor Closed (O16) = 1
Under
-voltage
System Contactor
Close (O15)
Under
-voltage
System Contactor
Closed (O16)