GE Industrial Solutions AF-300 G11 - Manual (Page 94)

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Data subject to change without notice 7/07. © 2007 GE Drives
H25 PID control (Feedback filter)
H 2 5 F B F I L T E R
Setting range: 0.0 to 60.0 seconds
This filter is for feedback signal input from Terminals 12 or
C1. This filter stabilizes operation of the PID control
system. A set value that is too large, however, deterio-
rates response.
H26 PTC thermistor (mode select)
H 2 6 P T C M O D E
Set value 0: Inactive
1: Active
Set this function active when the motor has a PTC
thermistor for overheat protection
Connect the PTC thermistor as shown in the figure below.
Turn on switch PTC on the control PCB. The trip mode is
activated by OH2: External thermal relay tripped.
Note: Must be 0 setting when using 4-20mA reference or
feedback signal and the PTC switch is off.
H27 PTC thermistor (level select)
H 2 7 P T C L E V E L
Setting range: 0.00 to 5.00V
The voltage input to Terminal C1 is compared to the set
voltage level. If the input voltage is equal to or greater
than the set voltage, H26 PTC thermistor (Mode select)
starts.
The PTC thermistor has its own alarm temperature. The
internal resistance value of the thermistor largely changes
at the alarm temperature. The operation voltage level is
set using this change in the resistance value.
The figure above for H26 PTC thermistor (Mode select)
shows that a 250W resistor and the thermistor (resistance
value Rp) are connected in parallel. Hence, voltage Vc1 at
Terminal C1 can be calculated using the following formula:
Vc
1
X 10 [V]
250 • Rp
250 + Rp
1000+
250 • Rp
250 + Rp
The operation level can be set by bringing Rp in the Vc1
calculation formula into the following range.
Rp1 < Rp < Rp2
To calculate Rp, use the following formula:
Rp
Rp 1 + Rp 2
[Ohm]
2
H28 Droop operation
H 2 8 D R O O P
Set value : -9.9Hz to 0.0Hz
When two or more drive motors operate a single machine,
a higher load is placed on the motor that is rotating the
fastest. Droop operation achieves a good load balance by
applying drooping characteristics to speed against load
variations.
Calculate the droop amount using the following formula:
Droop amount = Base frequency X
Speed droop at rated torque [r/min.]
[Hz]
Synchronous speed [r/min.]