RUN MED: Service & Maintenance Manual - rev. 1.0
SW or HW problems with the AT driver itself, etc....) it halts the motor and sends an alarm signal to
the display board, which displays a “THE EQUIPMENT IS BLOCKED” error message which can
be associated with different inverter error codes.
In addition, to protect the motor from overheating, each motor phase has a thermal cut-out
connected in series. If the temperature exceeds the threshold value, the thermal cut-outs open and
interrupt the circuit. The AT driver detects this condition as the opening of a NC external contact.
In such a case the AT driver halts the motor and outputs an alarm signal to the display board which
displays the “THE EQUIPMENT IS BLOCKED” message.
If the AT driver no longer receives the feedback signal from the encoder, it stops with error code
EAC and the machine displays the “SPEED ERROR” message. If the machine is turned off and on
again it will resume operation in open loop mode, that is to say ignoring the encoder signal. Closed
loop operation can only be resumed, obviously after having resolved the problem, by resetting
parameter PAR 13 to 0.
3.2.3. THE SIGNALS INVOLVED
The machine uses the following control signals:
• RS-485 Signal
This is a digital signal exchanged between the AT driver and the display board.
• Variable frequency VAC signal
This is the variable alternating-voltage signal output by the AT driver (pins 1-2-3 connector J5)
to supply the motor. Increasing the frequency of this signal increases the motor speed. The
frequency of the sinusoidal supply voltage sent by the AT driver to the motor can be viewed on
the display using the inverter manual test described at the paragraph 6.1.2.2 “Man. Inverter
Test”.
• Thermal cut-out 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 AT driver (pins 4-5 of connector J5).
When this input signal is an open contact, the AT driver detects the alarm, halts the motor and
sends an alarm signal over the RS-485 line to the display board.
• Encoder Pulses
The rotation of the motor causes a train of pulses between 0 and 5 Vdc to be sent (pins 1-2 and
pins 4-2 of connector J5) to the AT driver. This provides a feedback signal of the effective
motor speed. When measured with a multimeter, the signal is 4.8 Vdc with the motor halted and
2.6 Vdc when the motor is running.
Page 3.7
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