Epson RC420, Manual

Page: 18 / 172

Setup & Operation 1. Safety
8 RC420 Rev.9
Low Power Mode
The motor power is reduced in this mode.
Executing a power status change instruction will change to the restricted (low power)
status regardless of conditions of the safety door or operation mode. The restricted (low
power) status ensures the safety of the operator and reduces the possibility of peripheral
equipment destruction or damage caused by careless operation.
Dynamic Brake
The dynamic brake circuit includes relays that short the motor armatures. When the
motor armatures are shorted, the power to the Motor Driver modules is cut off and the
reverse EMF caused by the short stops the motors. The dynamic brake circuit is
activated when there is an Emergency Stop input or when any of the following errors is
detected: encoder cable disconnection, motor overload, irregular motor torque, motor
speed error, servo error (positioning or speed overflow), irregular CPU, memory
check-sum error and overheat condition inside the Motor Driver Module.
Encoder Cable Disconnection Error Detection
The dynamic brake circuit is activated when the Motor Encoder Signal cable is
disconnected.
Motor Overload Detection
The dynamic brake circuit is activated when the system detects that the load on the motor
has exceeded its capacity.
Irregular Motor Torque (out-of-control manipulator) Detection
The dynamic brake circuit is activated when irregularity with motor torque (motor output)
is detected (in which case the Manipulator is out of control).
Motor Speed Error Detection
The dynamic brake circuit is activated when the system detects that the motor is running
at incorrect speed.
Positioning Overflow-Servo Error-Detection
The dynamic brake circuit is activated when the system detects that the difference
between the Manipulator’s actual position and commanded position exceeds the margin
of error allowed.
Speed Overflow-Servo Error-Detection
The dynamic brake circuit is activated when the Manipulator’s actual speed is detected to
mark an overflow (the actual speed is outside the nominal range) error.