Let's put all of this information to practical use. Using the AMTEC Integrated Manufacturing System Simulator we can run through a typical procedure to put the equipment into a Electrically Safe Working Condition (ESWC):
Identify the equipment to be worked on:
AMTEC Integrated Manufacturing System Simulator
Electrical Energy Sources:
Pneumatic Energy Sources:
Hydraulic Energy Sources:
Kinetic Energy Sources: Always present during operation.
Potential Energy Sources: Charged capacitors, hydraulic hoses under pressure, etc.
Arc Flash Label
Let's review the following information on an Arc Flash label:
The Arc Flash label shown in Figure 2 is for a particular AIMSS installation which depicts a Category 2 Arc Flash PPE rating as a result of an Arc Flash Risk Analysis performed by a qualified person. This is determined by several factors including available voltage and upstream current limiting device clearing times. Since the PPE category level was stated, the optional incident energy level was not required. The label displays the Restricted Approach Boundary as "Shock Protection Boundary" and does not indicate the Limited Approach Boundary, which are not minimum required elements of an Arc Flash label. Note that each equipment installation is different and no single label can provide the necessary information for all similar equipment.
PPE Category Level 2 Equipment Required:
According to this Arc Flash label, the equipment is rated at an system voltage of 480 VAC and an Arc Flash Protection Boundary of 48 Inches, specifies a Category 2 level of PPE:
NOTE: Non-melting, non-flame resistant undergarments (such as 100% cotton underwear) may be worn under arc-rated outerlayers as long as they are not exposed to potential arc flash.
ESWC and Test Verification:
(1) Notify any affected personnel that the equipment will be de-energized and locked out.
(2) Using the Energy Control and Power Lockout (ECPL) placard on the main electrical control panel, locate and identify all power sources and their disconnecting devices (use up-to-date drawings if necessary). Make sure the device used to disconnect and lockout the power source is properly identified to the ECPL sign.
Ensure all potential energy sources to be de-energized are identified as well.
On the AIMSS, the a following devices will need to have their potential energy dissipated, bleed off or blocked out if working in these areas:
(3) Make sure the equipment is in a non-operational state at the control panel. Use the normal operating shut-down procedure it the equipment is in operating mode.
(4) De-energize the simulator. (NOTE: For the purposes of this training and to ensure the safety of the students and faculty, disconnect the external switch mounted on the side of the simulator cabinet, upstream (line side) of the main electrical disconnect on the panel. Make sure to follow the same procedures as when disconnecting any power source.)
To do this, stand off to the side and place the main electrical disconnect switch to the OFF position.
(5) Apply a properly identified lockout device (padlock) to the disconnect according to a documented policy. Ensure the key remains in your possession at all times. The person who placed the lockout device is responsible for its removal.
(6) Disable, restrain or dissipate all potential energy sources (discharging, disconnecting, bleeding off, etc.). Identify the possible sources of stored electrical energy (example: capacitors) and ground the phase conductor or circuit parts.
Note that only those devices in the area in which the work needs to be performed have to be de-energized and locked out.
(7) The next step is to verify the equipment is de-energized. Ensure that no personnel are near the affected equipment, then try to operate by pressing the operating controls (push button, switch, etc.). Verify the equipment is de-energized by verifying with a test instrument capable of detecting voltage. Important: Place the equipment into the "OFF" or non-operational mode after operational verification is complete.
Make sure the testing instrument (volt meter) and its accessories are rated for the maximum working voltage and designed for the conditions in which they will be used.
For example: the AIMSS is rated for 480 VAC, add 5% for a safety margin, the minimal system voltage is 504 VAC, a voltage meter rated for up to 600 VAC minimum is required.
It is mandatory to verify the test instrument (volt meter) prior to use to check for the presence or absence of voltage, and again after checking, by verifying it against a known voltage source.
Once donned with the appropriate PPE, test the equipment for the presence or absence of voltage using the following steps:
Step 1: Test the instrument against a known voltage (such as a wall socket or extension cord). It must indicate the known voltage to verify the test instrument is operating properly.
Step 2: Immediately test the equipment for a de-energized state (<1V - stray voltage). Test for voltage to ground and voltage between conductors (phase to phase).
For the AIMSS this would be performed at the Main Disconnect Switch:
Step 3: Confirm the test instrument for failure by retesting at the known voltage source(such as a wall socket or extension cord). It must indicate the known voltage to verify the test instrument is operating properly.
(8) The equipment is now locked out.
Remember to treat all electrical circuits and parts as energized until ALL sources of energy are accounted for and de-energized.
The process as previously described will place the equipment into an Electrically Safe Working Condition (ESWC) to work on without PPE. This would be applicable if changing wiring, adding a PLC module, changing a VFD drive, or similar task.
To re-energize the AMTEC Integrated Manufacturing System Simulator:
(1) Replace all guarding, covers, circuit protectors that may have been removed during service. Remove all non-essential items from the area.
Close all panel doors and secure with locking handle or screws.
(2) Confirm that all personnel are notified of the impending re-energizing and are safely positioned away from the affected equipment.
(3) Verify the controls are in a safe non-operating mode.
(4) Remove your lockout device. If there is more than one device attached, do not remove them and skip the next step. Remove any energy isolating devices. It may be necessary to remove some types of blocking after re-energization.
Standing off to one side, place the disconnect switch into the ON position. The equipment is now energized and should be treated as such.
(5) Notify affected employees that the servicing or maintenance is completed and the machine or equipment is ready for use.
Exit the arc flash boundary and remove PPE.
There are three external power distribution cables and disconnects/lockouts at the rear of the control panel to remote components on the conveyor system that will be de-energized when the main electrical disconnect is disabled. They can be used to disable power downstream of the main control panel if necessary.
They are identified as follows:
The robot control panel (on some units) have a separate electrical disconnect which will disable power to the controller unit and robot. However, be aware that power may remain on for certain safety circuits. Robot controller may be locked out at the main control panel disconnect switch, safety switch or external power distribution cable disconnect (blue).
Any troubleshooting and testing of the equipment with the power ON and within the arc flash/shock boundaries is only allowed with the proper PPE and training.
Figure 1: AIMSS - AMTEC Integrated Manufacturing System Simulator
Figure 2: AIMSS Category 2 PPE Arc Flash Label Example
Figure 3: AIMSS Main Electrical Lockout Switch and ECPL Sign
Figure 4: AIMSS Dissipate/Disable Energy Sources
Figure 5: AIMSS External Main Electrical Disconnect Switch
Figure 6: AIMSS Verify LOTO–Attempt to Start at Control Panel
Figure 7: AIMSS Main Disconnect Switch and Distribution Block
Figure 8: AIMSS External Power Disconnects/Lockouts