36
VLT
®
Series 3500
Example 2:
In a ventilating system, the ability to reverse the fan in the
case of fire is required.
The control signal used is 4 to 20 mA, corresponding to
10 to 100% motor speed, typically 6 to 60 Hz.
A remote indication of motor speed is required. The
signal for that is to be 4 to 20 mA, with 4 mA
corresponding to 0 Hz, and 20 mA corresponding to 60
Hz.
The following must be programmed:
Function Parameter # Parameter Value Data Value #
Safety interlock 003 KEY HOA w. stp [1]
Minimum frequency 201 6 Hz
Maximum frequency 202 60 Hz
0-f
MAX
407 f
MAX
=4 to 20 mA [20]
Reference (voltage) 412 No operation [0]
Reference (current) 413 4 to 20 mA [2]
NOTE:
A shield for control wires is to be connected in
accordance with the installation instructions.
All settings are based on factory settings.
Be sure to check the motor data settings (parameters
104, 105 and 107, or the Quick Setup menu items 1, 2
and 3). They must be set based upon the actual motor
used.
1 = Start/Stop
2 = Reversing
3 = 4 to 20 mA output speed signal
4 = 4 to 20 mA input speed reference
External safety interlocks can be connected between
terminals 12 and 27.
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