Risk Assessment; Residual Risk (Common); Residual Risk (Specific To Each Function) - Mitsubishi Electric MELFA CR800 Series Instruction Manual

1 FUNCTIONS AND CONFIGURATION

1.4 Risk Assessment

To ensure safety, the user needs to assess all the risks and determine residual risks for the mechanical system
as a whole. Companies or individuals who configure the system will accept full responsibility for installation and
authorization of the safety system. Assessment for all risks and safety level certification are required for the
equipment/system as a whole. The following shows residual risks related to the safety monitoring function of this
product.

Residual Risk (Common)

1.4.1
(1) If the origin setting, parameter settings or programs of the robot are incorrect, unexpected operation may occur
and safety cannot be ensured. Fully check whether operations are as intended.
(2) Until correct installation, wiring, and adjustment are achieved, safety cannot be ensured.
(3) Only a qualified person is given the authority to install, start, repair, adjust, etc. the equipment to which
devices are installed. Installing or operating the equipment should be done by a trained engineer.
(4) For the safety monitoring function, perform the wiring separately from other signal wirings.
(5) Protect cables by appropriate means (installing inside the control panel, using a cable guard, etc.).
(6) It is recommended to use switches, relays, sensors, etc. conforming to safety standards. For using switches,
relays, sensors, etc. not conforming to safety standards, sufficient verification of safety is necessary on the
customer side.
(7) The safety function only works for the robot controller and the robot. The function covers no additional axes
(additional robot axes, user mechanisms). When using an additional axis, the customer needs to ensure and
assess the safety of the axis.
(8) To perform the initial test of the robot, power cycle it regularly. The initial test should be performed at least
every six months.

Residual Risk (Specific to Each Function)

1.4.2
(1) STO function
This function interrupts transmission of power to the motor installed in the robot arm, and may bring variation to
the posture of the robot arms due to mechanical factors, such as a timing belt break or brake wear, etc. of the
robot arm. Periodic maintenance of the robot arm is required. Depending on the posture of the robot, the arm may
droop if the axis does not have a brake.
(2) SS1function
This function controls and decelerates the motor speed installed to a robot arm. The movement cannot be stopped
immediately after deceleration is started.
(3) SS2 function
This function controls and decelerates the motor speed installed to a robot arm. The movement cannot be stopped
immediately after deceleration is started.
(4) SOS function
This function monitors motors installed in the robot so that they stay at rest. Mechanical factors, such as break of
timing belts of the robot, may bring variation to the posture of the robot. Periodic maintenance of the robot arm is
required.
(5) SLS function
This function monitors the speed of each part of the robot arm and tools specified beforehand. Depending on the
robot posture, some undefined parts may move at a speed higher than the monitoring speed.
This function is only enabled when the robot is in the servo-on state and therefore does not monitor the speed
when the robot is in the servo-off state.
1-6 Risk Assessment