semi合集-English.pdf - 第6785页

SEMI S2-0703a E © SEMI 1991, 2004 14 12.3 The em ergency of f button should be re d and mushroom shaped. A yellow back ground for the EMO should be provi d ed. NOTE 37: Non-lockable self-latching (i.e., twist- or pull-to…

SEMI S2-0703a

12 Emergency Shutdown

12.1 The equipment should have an “emergency off”

(EMO) circuit. The EMO actuator (e.g., button), when

activated, should place the equipment into a safe

shutdown condition, without generating any additional

hazard to personnel or the facility.

EXCEPTION 1: An EMO circuit is not needed for

equipment rated 2.4 kVA or less, where the hazards are

only electrical in nature, provided that the main

disconnect meets the accessibility provisions of Section

12.5.2 and that the effect of disconnecting the main

power supply is equivalent to activating an EMO

circuit.

EXCEPTION 2: Assemblies that are not intended to be

used as stand-alone equipment, but rather within an

overall integrated system, and that receive their power

from the user’s system, are not required to have an

emergency off circuit. The assembly’s installation

manual should provide clear instructions to the

equipment installer to connect the assembly to the

integrated system’s emergency off circuit.

NOTE 33: It is recommended that the emergency off

function not reduce the effectiveness of safety devices or of

devices with safety-related functions (e.g., magnetic chucks or

braking devices) necessary to bring the equipment to a safe

shutdown condition effectively.

NOTE 34: If a fire detection or suppression system is

provided with the equipment, see Section 14 for additional

information.

12.1.1 If the supplier provides an external EMO

interface on the equipment, the supplier should include

instructions for connecting to the interface.

12.2 Activation of the emergency off circuit should

deenergize all hazardous voltage and all power greater

than 240 volt-amps in the equipment beyond the main

power enclosure.

EXCEPTION 1: A non-hazardous voltage EMO circuit

(typically 24 volts) and its supply may remain

energized.

EXCEPTION 2: Safety related devices (e.g., smoke

detectors, gas/water leak detectors, pressure

measurement devices, etc.) may remain energized from

a non-hazardous power source.

EXCEPTION 3: A computer system performing

data/alarm logging and error recovery functions may

remain energized, provided that the energized

breaker(s), receptacle(s), and each energized conductor

termination are clearly labeled as remaining energized

after EMO activation. Hazardous energized parts that

remain energized after EMO activation should be

insulated or guarded to prevent inadvertent contact by

maintenance personnel.

EXCEPTION 4: Multiple units mounted separately

with no shared hazards and without interconnecting

circuits with hazardous voltages, energy levels or other

potentially hazardous conditions may have:

 separate sources of power and separate supply

circuit disconnect means if clearly identified, or

 separate EMO circuits, if they are clearly

identified.

12.2.1 The EMO circuit should not include features

that are intended to allow it to be defeated or bypassed.

12.2.2 The EMO circuit should consist of

electromechanical components.

EXCEPTION 1: Solid-state devices and components

may be used, provided the system or relevant parts of

the system are evaluated and found suitable for use.

The components should be evaluated and found suitable

considering abnormal conditions such as over voltage,

under voltage, power supply interruption, transient over

voltage, ramp voltage, electromagnetic susceptibility,

electrostatic discharge, thermal cycling, humidity, dust,

vibration and jarring. The final removal of power

should be accomplished by means of electromechanical

components.

EXCEPTION 2: FECS may be used provided the FECS

conforms to an appropriate standard for electronic

safety systems. Components of the FECS should be

tested and certified according to the requirements of the

standard used. IEC 61508 and ISO 13849-1 (EN 954-

1) are examples of internationally recognized electronic

safety systems standards. The final removal of power

should be accomplished by means of electromechanical

components.

NOTE 35: Paragraph 13.4.3 states additional assessment

criteria for safety-related components and assemblies.

NOTE 36: A FECS is a subsystem of a (PES) Programmable

Electronic System. IEC 61508 is the preferred standard for

complex PES.

12.2.3 All EMO circuits should be fault-tolerant.

12.2.4 Resetting the EMO switch should not re-

energize circuits, equipment, or subassemblies.

12.2.5 The EMO circuit should shut down the

equipment by deenergizing rather than energizing

control components.

12.2.6 The EMO circuit should require manual

resetting so that power cannot be restored

automatically.

SEMI S2-0703a

12.3 The emergency off button should be red and

mushroom shaped. A yellow background for the EMO

should be provided.

NOTE 37: Non-lockable self-latching (i.e., twist- or pull-to-

release) EMO buttons may be required by regulations.

12.4 All emergency off buttons should be clearly

labeled as “EMO,” “Emergency Off,” or the equivalent

and should be clearly legible from the viewing location.

The label may appear on the button or on the yellow

background.

12.5 Emergency off buttons should be readily

accessible from operating and regularly scheduled

maintenance locations and appropriately sized to enable

activation by the heel of the palm.

12.5.1 Emergency off buttons should be located or

guarded to minimize accidental activation.

12.5.2 No operation or regularly scheduled

maintenance location should require more than 3 m (10

feet) travel to an EMO button.

12.5.3 The person actuating or inspecting the EMO

button should not be exposed to serious risks of tripping

or falling or of coming in contact with energized

electrical parts, moving machinery, surfaces or objects

operating at high temperatures, or other hazardous

equipment.

12.6 See Section 13.5 for additional EMO guidelines

when EMOs are used with UPSs.

13 Electrical Design

13.1 This section covers electrical and electronic

equipment that use hazardous voltages.

13.2 Types of Electrical Work — The following are the

four types of electrical work defined by this guideline:

Type 1 — Equipment is fully deenergized.

Type 2 — Equipment is energized. Energized circuits

are covered or insulated.

NOTE 38: Type 2 work includes tasks where the energized

circuits are or can be measured by placing probes through

suitable openings in the covers or insulators.

Type 3 — Equipment is energized. Energized circuits

are exposed and inadvertent contact with uninsulated

energized parts is possible. Potential exposures are no

greater than 30 volts rms, 42.4 volts peak, 60 volts dc or

240 volt-amps in dry locations.

Type 4 — Equipment is energized. Energized circuits

are exposed and inadvertent contact with uninsulated

energized parts is possible. Potential exposures are

greater than 30 volts rms, 42.4 volts peak, 60 volts dc,

or 240 volt-amps in dry locations. Potential exposures

to radio-frequency currents, whether induced or via

contact, exceed the limits in Table A5-1 of Appendix 5.

13.3 Energized Electrical Work — The supplier should

design the equipment to minimize the need to calibrate,

modify, repair, test, adjust, or maintain equipment

while it is energized, and to minimize work that must

be performed on components near exposed energized

circuits. The supplier should move as many tasks as

practical from category Type 4 to Types 1, 2, or 3.

Routine Type 4 tasks, excluding troubleshooting,

should have specific written instructions in the

maintenance manuals. General safety procedures (e.g.,

wearing appropriate Personal Protective Equipment and

establishing barriers) for troubleshooting, including

Type 4 work, should be provided.

13.4 Electrical Design — Equipment should conform

to the appropriate international, regional, national or

industry product safety requirements.

13.4.1 Nonconductive or grounded conductive physical

barriers should be provided:

 Where it is necessary to reach over, under, or

around, or in close proximity to hazards.

 Where dropped objects could cause shorts or

arcing.

 Where failure of liquid fittings from any part of the

equipment would result in the introduction of

liquid into electrical parts.

 Over the line side of the main disconnect.

 Where maintenance or service tasks on equipment

in dry locations are likely to allow inadvertent

contact with uninsulated energized parts containing

either: potentials greater than 30 volts rms, 42.4

volts peak, or 60 volts dc; or power greater than

240 volt-amps.

NOTE 39: A dry location can be considered to be one that is

not normally subject to dampness or wetness.

NOTE 40: Removable nonconductive and noncombustible

covers are preferred.

13.4.2 Where test probe openings are provided in

barriers, the barriers should be located, and the probe

openings should be sized, to prevent inadvertent contact

with adjacent energized parts, including the energized

parts of the test probes.

13.4.3 Where failure of components and assemblies

could result in a risk of electric shock, fire, or personal

injury, those components and assemblies should be

certified by an accredited testing laboratory and used in

accordance with the manufacturer’s specifications, or

otherwise evaluated to the applicable standard(s).

SEMI S2-0703a

NOTE 41: With the exception of implementation of ground

fault protection, shunt trip units that require power to trip

(actuate) are not recommended to be used in a safety control

circuit, because they are not fail-safe.

13.4.4 Electrical wiring for power circuits, control

circuits, grounding (earthing) and grounded (neutral)

conductors should be color coded according to

appropriate standard(s) per Section 13.4, or labeled for

easy identification at both ends of the wire. Where color

is used for identification, it is acceptable to wrap

conductor ends with appropriate colored tape or

sleeving; the tape or sleeving should be reliably secured

to the conductor.

EXCEPTION 1: Internal wiring on individual

components, e.g., motors, transformers, meters,

solenoid valves, power supplies.

EXCEPTION 2: Flexible cords.

EXCEPTION 3: Nonhazardous voltage multi-conductor

cables (e.g., ribbon cables).

EXCEPTION 4: When proper color is not available for

conductors designed for special application (e.g., high-

temperature conductors used for furnaces and ovens).

13.4.5 Grounding (earthing) conductors and connectors

should be sized to be compatible in current rating with

their associated ungrounded conductors according to

appropriate standard(s) per Section 13.4.

13.4.6 Electrical enclosures should be suitable for the

environment in which they are intended to be used.

13.4.7 Enclosure openings should safeguard against

personnel access to uninsulated energized parts. (Refer

to Appendix 1 for examples of openings for protection

against access from operators.)

13.4.8 Top covers of electrical enclosures should be

designed and constructed to prevent objects from

falling into the enclosures. (Refer to Appendix 1 for

examples of acceptable top enclosure openings.)

13.4.9 The current interrupting capacity (also known as

amperes interrupting capacity, or AIC) of the

equipment main disconnect should be identified in the

facility installation and maintenance manuals.

13.4.10 The equipment should be provided with main

overcurrent protection devices and main disconnect

devices rated for at least 10,000 rms symmetrical

amperes interrupting capacity (AIC).

NOTE 42: Some facilities may require higher AIC ratings

due to electrical distribution system design.

EXCEPTION: Cord- and plug-connected single phase

equipment, rated no greater than 240 volts line-to-

line/150 volts line-to-ground and no greater than 2.4

kVA, may have overcurrent protection devices with

interrupting capacity of at least 5,000 rms symmetrical

amperes interrupting capacity (AIC).

13.4.11 Equipment should be designed to receive

incoming electrical power from the facility to a single

feed location that terminates at the main disconnect

specified in Section 13.4.9. This disconnect, when

opened, should remove all incoming electrical power in

the equipment from the load side of the disconnect. The

disconnect should also have the energy isolation

(“lockout”) capabilities specified in Section 17.

EXCEPTION 1: Equipment with more than one feed

should be provided with provisions for energy isolation

(lockout) for each feed and be marked with the

following text or the equivalent at each disconnect:

“WARNING: Risk of Electric Shock or Burn.

Disconnect all [number of feed locations] sources of

supply prior to servicing.” It is preferred that all of the

disconnects for the equipment be grouped in one

location.

EXCEPTION 2: Multiple units mounted separately

with no shared hazards and without interconnecting

circuits with hazardous voltages, energy levels or other

potentially hazardous conditions may have:

 separate sources of power and separate supply

circuit disconnect means, if they are clearly

identified; or

 separate EMO circuits, if they are clearly

identified.

13.4.12 A permanent nameplate listing the

manufacturer’s name, machine serial number, supply

voltage, phase, frequency and full-load current should

be attached to the equipment where plainly visible after

installation. Where more than one incoming supply

circuit is to be provided, the nameplate should state the

above information for each circuit.

NOTE 43: Additional nameplate information may be

required depending on the location of use.

13.5 Uninterruptable Power Supplies (UPSs) — This

section applies to UPSs with outputs greater than: 30

volts rms, 42.4 volts peak; 60 volts dc; or 240 volt-

amps.

13.5.1 Whenever a UPS is provided with the

equipment, its location and wiring should be clearly

described within the installation and maintenance

manual.

13.5.2 Power from the UPS should be interrupted when

any of the following events occur:

 the emergency off actuator (button) is pushed; or

 the main equipment disconnect is opened; or