Technogym Forma Service Maintenance Manual page 29

FORMA: Service & Maintenance manual - rev. 3.0
• Speed reference signal
This is the signal generated by the CPU board (pin 4-12 on connector K4) to control the motor
speed. It is a PWM signal, i.e. a fixed-frequency square wave signal with variable duty cycle.
The logic of this control has the duty cycle decreasing with increasing speed, from a maximum
of approximately 5 Vdc down to a few hundred mVdc.
The signal enters the driver board (pin 4-12 on connector J5), is converted into a variable analog
signal between 0 and 10 Vdc, and sent out (pin 5-6 on connector J5 of the driver board) to the
inverter (pin O-L). The signal input to the inverter increases with increasing speed.
The relationship between the speed reference voltage and the inverter output frequency is
determined by the values of the configuration parameters in the inverter program.
• Variable frequency VAC signal
This is the variable frequency alternating voltage generated by the inverter (pin U-V-W) for
supplying the motor. The motor speed increases with increasing frequency.
• Thermal cutout signal
Each motor phase is equipped with a normally-closed thermal cutout which opens when the
temperature exceeds a preset threshold. The 3 thermal cutouts are connected in series and exit
the motor via a 2-wire cable connected to the inverter (3-P24). The inverter is programmed to
expect a NC signal on these pins. When at least one thermal cutout is tripped, the contact opens
and the inverter, detecting the open-circuit condition, generates an alarm signal.
• Alarm signal
This is the signal generated by the inverter (AL1-AL0) if a problem is detected in the motor
drive, or if the motor thermal cutouts open. It enters the driver board (pin 3-4 on connector J5)
and its value is 0 Vdc under normal conditions, 5 Vdc under alarm conditions.
The signal is then sent from the driver board (pin 8-12 on connector J6) to the CPU board (pin
8-12 on connector K4); its value is 0.2 Vdc under normal conditions, 5 Vdc under alarm
conditions. When this alarm signal switches to 0 Vdc, the CPU disables the Start signal, resets
the PWM signal and shows error message "E3" on the display.
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