Emerson Mini Maestro DCD60x10/20, Руководство пользователя

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20
Mini Maestro User Guide
www.controltechniques.com Issue Number: 5
4.3 Making adjustments to the drive
Zero speed offset
ZERO REF potentiometer
1. Connect the non-inverting input of the speed reference signal to terminal 9 and the
inverting input to terminal 10.
2. Set the speed reference signal for zero speed.
3. Apply +10V to +30V to terminal 7
Drive Enabl e.
4. Connect a digital multimeter to pins 11 and 12.
5. Enable the drive and adjust the ZERO REF potentiometer to reduce the multimeter
reading to not more than 1mV.
6. Restore the original wiring.
Maximum speed
RT resistor
Use the following equation to calculate the value of the RT resistor:
RT = 400 [(Vm x Ke
tacho
) - 5
Ω
]
Where:
Vm = Maximum speed of motor in RPM ÷ 1000
Ke
tacho
= Tachogenerator voltage constant (voltage output at 1000 RPM) and in
general Ke
tacho
= V * 1000 / RPM
Resistor ratings:
Power: 0.25W
Tolerance: +20%.
Example
Max required speed = 3000 RPM
∴
Vm = 3
Tachogenerator output = 7V at 1000 RPM
∴
Ke
tacho
= 7
Calculate:
RT = 400 [ (3 x 7) - 5
Ω
] = 6.4k
Ω
The nearest suitable value is 6.8k
Ω
.
A 10k
Ω
RT resistor is fitted as standard. This value is suitable for tachogenerator
voltage constant, Ke
tacho
= 10 and maximum motor speed = 3000 rpm.
NOTE
If the calculated value of RT is zero, fit a jumper instead of a resistor
If the calculated value is negative, the tachogenerator must be changed for one with a
greater value of Ke
tacho
in order for the motor to reach the required speed.
NOTE