Parameter and variable descriptions 6-21 – Rockwell Automation 1557 MEDIUM VOLTAGE AC DRIVE User Manual
Page 77
PARAMETER AND VARIABLE DESCRIPTIONS
6-21
1557-UM050F-EN-P – June 2013
Pulse Number [Pulse number]
Linear number:
153
Minimum value:
6
Maximum value:
18
(FRN5.xx)
12
(FRN4.xx)
Default value:
6
This parameter specifies the pulse number (6, 12, or 18) of the line converter. If this parameter is changed, the
control power must be turned off and on before the new value takes effect.
Warning: Setting this parameter to the wrong value may cause multiple failures of line converter thyristors.
CT Configuration [CT configuration]
Linear number:
154
Minimum value:
2
Maximum value:
3
Default value:
2
This parameter specifies the number of current transformers per bridge for 12-pulse drives. Set this parameter
to 2 for drives with 2 CT’s on the master bridge only, and to 3 for drives with 3 CT’s on both the master and
slave bridges. If the wrong value is entered for this parameter, the line current feedback scaling will be wrong.
This parameter was added in Rev 4.72 and is not present in 5.xx
PWM Frequency Maximum [PWM freq maximum]
Linear number:
155
Minimum value:
200 Hz
Maximum value:
280 Hz or 560 Hz (FRN 5.30)
Default value:
200 Hz
This parameter specifies the maximum GTO switching frequency. All PWM mode transition frequencies are
proportional to this parameter. The 560 Hz maximum applies to Powerflex drives only. Bulletin 1557 drives
rated less than 4000V and 2000 KW are automatically limited to 225 Hz maximum.
Flux Minimum [Flux minimum]
Linear number:
156
Minimum value:
0.20 pu
Maximum value:
2.00 pu
Default value:
0.40 pu
This parameter specifies the minimum flux level for operation in the normal running mode. It is normally set to
0.40 pu.
CT Ratio Ground Fault [CT ratio gnd flt]
Linear number:
157
Minimum value:
10
Maximum value:
10000
Default value:
2000
This parameter specifies the ratio of the current transformer used to measure the ground fault (zero sequence)
current at the input of the drive.
NOTE: When
upgrading the firmware from a revision prior to 3.40, the bridge rectifier on the secondary of the
ground fault CT should be removed, but the burden resistor and zener diodes should be retained unchanged.
CT Burden Ground Fault [CT burden gndflt]
Linear number:
158
Minimum value:
10 ohms
Maximum value:
10000 ohms
Default value:
1000 ohms
This parameter specifies the value of the scaling resistor used for the ground fault current feedback.