Zapi EPS-AC, Руководство по эксплуатации и инструкция пользователя, Страница: 49 / 52

Page 49
12 SAFETY CONTROLS AND THEIR USE
12.1 SAFETY CONTROLS IN TACHO-GENERATOR AND AUTOMATIC CENTERING
STEERING
The following malfunctioning conditions are tested on electrical manual steering:
1)
Safety on motor wires broken.
2) Safety on failures of the steering wheel tacho-generator or stepper motor.
3) Safety on the presence of current when the steering motor is at rest.
4) Safety on the presence of phase voltage when the steering motor is at rest.
5) Safety on pot wires broken (for automatic centering operation).
6) Cross diagnosis between Master and Supervisor microcontroller.
All of these alarm conditions cause a relay to open that will remove the enabling drive.
Here is a detailed look at them.
12.2 SAFETY ON MOTOR WIRES BROKEN
If the current on at least one of the motor phases is detected as less than 6Aac when
the motor frequency is other than 0Hz an alarm will occur. The delay for alarm occuring
decreases as the motor frequency increases. For a motor frequency higher than 50Hz
this alarm will occur with a 100msec delay. If the steady state motor current is less than
6Aac this alarm could unwillingly occur.
12.3 SAFETY ON FAILURE OF THE STEERING TACHO-GENERATOR
The safety on tacho-generator failure detects the presence on the line of the tach-
generator impedance (22 ohms resistance and 6 mH inductance). This is possible by
using it as a load for an astable oscillator. It is therefore possible to detect defects due
to disconnection and short circuiting the tacho-generator. The tacho-generator
impedance is about 40 ohms. So when an impedance lower than 15 ohms and higher
than 300 ohms is detected, an alarm occurs in less than 100msec.
12.3.1 Safety on failures of the steering stepper motor
The safety on stepper motor failures detects the presence of the stepper motor phases
resistance (30 ohms). A biasing current is injected in both the D (CNB pin #3) and Q
(CNB pin#9) lines for testing. When at least one of these currents is broken off an alarm
occurs in less than 100msec.
12.4 SAFETY ON THE PRESENCE OF CURRENT WHEN THE STEERING MOTOR
IS AT REST
The microprrocessor logic continuously tests the current amplifiers output at rest and if
they are other than 2.5Vdc±0.15Vdc, causes an alarm. These voltage are measured
between D46 and D45 anodes and gnd (see figure 11.1.6.1).