Eurotherm Drives 590 DRV Digital, Product Manual, Page: 32 / 318

Chapter 3 Installation and Wiring
3 - 10
3
590 DRV Digital DC Drive Product Manual
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A switchable calibration card ships with all 590 DRV Digital drives rated through 400 HP. Models
rated 500 HP and above ship with a resistor calibration card. You can order the resistor card on lower
horsepower models as an option.
NOTE. The drive must use the switchable tachometer generator feedback board if using
the switchable calibration card.
WARNING!
Do not swap calibration boards or change any board settings while applying power to the
590 DRV Digital drive. Do not interchange calibration boards or switch the calibration
settings without first verifying that they match the motor's nameplate rating. Mechanical
damage and injury to personnel can result.
Resistor Calibration Card (AH058529U001)
Resistor values on the card scale the
controller to the motor armature current,
AC of DC tachometer generator feedback,
armature voltage feedback, field current,
and field voltage. Use the formulas below
to determine the correct resistor values for
your application.
Calibration resistors should be of good
quality metal film type, 2 percent toler-
ance, ¼ watt (or better). Actual resistance
values should measure within ±10 percent
of the calculated values.
Armature Current
Calibration
Must use Switch
Tach Board if
Using Switch Cal
Card
1. Armature current calibration
The parallel connection of resistors R1, R2, R3, R4, and R5 calibrates the drive to the motor
armature current. The combined value R
IA
of all these resistors is calculated as follows:
R
IA
= 2200
W
(Full Load Current – 1)
You can verify this value by using the formula:
1/R
IA
= 1/R1 + 1/R2 + 1/R3 + 1/R4 + 1/R5
NOTE. The armature current calibration scaling resistors for external stack controllers
(models rated 500 HP and greater) are fitted on the suppression board. See drawing
HC352526 at the end of Appendix F for the resistor location and sizing.
Caution
Use ½ watt, metal film type, 2 percent tolerance resistors for current calibration on
external stack controllers. Double this wattage rating for each 450 A of armature current.
2. Tachometer generator calibration
a. For full speed tachometer generator voltage up to 200 volts:
R6 + R7 = (Tachometer Generator Volts –10) k
W
Tachometer
Generator
Calibration
<200V Signal.
Figure 3.8 - Resistor Calibration Board