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SEMI S22-1103a © SEMI 2003, 2005 6 5.1.34 hazardous electrical power — po wer levels equal to or greater than 240VA. 5.1.35 insulation — a layer of non-conductive material used as the outer surface of a c onductor for th…

SEMI S22-1103a © SEMI 2003, 2005 5

5.1.14 disconnecting means — a device, or group of devices, or other means by which the conductors of a circuit

are intended to be disconnected from their source of supply.

5.1.15 door — a hinged enclosure panel.

5.1.16 double insulation — comprised of both supplementary insulation and basic insulation combined.

5.1.17 duct — an enclosed channel designed expressly for holding and protecting electrical conductors, cables, and

bus bars. Conduits, wireways and under-floor channels are types of ducts.

5.1.18 earthing — see protective earthing system.

5.1.19 electrical enclosure — a panel, compartment, or other defined area housing electrical components used to

enhance the safety of the equipment containing those components.

5.1.20 electrical feed — (referenced from the equipment) a facility supply conductor that provides electrical energy

to a piece of equipment.

NOTE 4: Electrical wiring from enclosure to enclosure, routed through the facility, but provided with the equipment to power

subsystems, are not considered electrical feeds.

5.1.21 energized — electrically connected to a source of voltage.

5.1.22 equipment — a specific piece of machinery, apparatus, process module, or device used to execute an

operation. The term “equipment” does not apply to any product (e.g., substrates, semiconductors).

5.1.23 exposed (as applied to energized parts) — capable of being inadvertently touched or approached nearer than

a safe distance by a person. It is applied to parts that are not suitably guarded, isolated, or insulated.

5.1.24 fail-safe — designed so that a failure does not result in an increased risk.

NOTE 5: For example, a fail-safe temperature limiting device would indicate an out-of-control temperature if it were to fail.

This might interrupt a process, but would be preferable to the device indicating that the temperature is within the control limits,

regardless of the actual temperature, in case of a failure.

5.1.25 Fail-to-safe equipment control system (FECS) — a safety-related programmable system of control circuits

designed and implemented for safety functions in accordance with recognized standards such as ISO 13849-1 (EN

954-1) or IEC 61508, ANSI SP 84. These systems (e.g. safety Programmable Logic Controller (PLC), safety-related

Input and output (I/O) modules) diagnose internal and external faults and react upon detected faults in a controlled

manner in order to bring the equipment to a safe state.

NOTE 6: A FECS is a subsystem to a (PES) Programmable Electronic System as defined in IEC61508 –4.

5.1.26 failure — the termination of the ability to perform an intended function. Failure is an event, as distinguished

from “fault,” which is a state.

5.1.27 fault — the state of an item characterized by the inability to perform its intended function; excludes the

inability to perform required functions during preventive maintenance or other planned actions, or due to lack of

external resources.

5.1.28 fault-tolerant — designed so that a reasonably foreseeable single point failure does not result in an unsafe

condition.

5.1.29 ground fault — an unintentional, electrically conducting connection between an ungrounded or grounded

conductor of an electrical circuit and the normally non-current-carrying conductors, metallic enclosures, metallic

raceways, or metallic equipment.

5.1.30 Ground-Fault-Circuit-Interrupter (GFCI) — a device intended for the protection of personnel that functions

to de-energize a circuit or portion thereof within an established period of time when a current to ground exceeds a

value in the range of 4 mA to 6 mA (for further information, see UL 943, Standard for Ground-Fault Circuit-

Interrupters).

5.1.31 grounding — see protective earthing system.

5.1.32 hazard — a condition that is a prerequisite to a mishap.

5.1.33 hazardous voltage — voltages greater than 30 Volts RMS, 42.4 Volts peak, or 60 Volts DC.

SEMI S22-1103a © SEMI 2003, 2005 6

5.1.34 hazardous electrical power — power levels equal to or greater than 240VA.

5.1.35 insulation — a layer of non-conductive material used as the outer surface of a conductor for the purpose of

protecting against electric shock.

5.1.36 interlock — a mechanical, electrical or other type of device or system, whose purpose is to prevent or

interrupt the operation of equipment subsystems under specified conditions.

5.1.37 interrupting capacity — the highest current at rated voltage that a device is intended to interrupt.

NOTE 7: Also known as amperes interrupting capacity (AIC).

5.1.38 isolated power system — a power system that has a high impedance between its conductors and the facilities

connection of the equipment. High impedance can be characterized by resistances of one meg-ohm or more.

Isolated power systems are supplied power by isolation transformers or power supplies that have no direct electrical

connection between their primary conductors and their secondary conductors.

NOTE 8: An isolation transformer with one leg of the secondary connected to ground is not an isolated power system.

5.1.39 main disconnecting means — a disconnecting means that is intended to be used to disconnect facilities

electrical power from the system.

5.1.40 maintenance — planned activities intended to keep equipment in proper working order (see also the

definition for service).

5.1.41 material group — a categorization of the Comparative Tracking Index (CTI) of an insulator as follows:

 Material Group I: 600 <= CTI

 Material Group II: 400 <= CTI < 600

 Material Group IIIa: 175 <= CTI < 400

 Material Group IIIb: 100 <= CTI < 175

5.1.42 maximum nominal load — the maximum continuous power a circuit will draw under operating conditions

prescribed by the manufacturer. Non-periodic power variations of less than a second in duration are not considered

continuous.

5.1.43 multi-outlet assemblies — assemblies whose primary function is to provide electrical connections and that

have multiple receptacles which are intended for electrical connections.

5.1.44 neutral conductor — an earthed (grounded) AC current carrying conductor.

NOTE 9: It is distinct from protective earthing which is an earthed (grounded) non-current carrying conductor or a non-earthed

(non-grounded) current carrying conductor.

5.1.45 normal operating conditions — the condition of the equipment reasonably foreseen by the manufacturer,

including specified conditions of use, during operation, maintenance and servicing while the equipment is operated,

maintained and serviced according to the manufacturer’s instructions and with no unauthorized equipment

modifications. Normal operating conditions should include consideration of reasonably foreseeable misuse.

5.1.46 operator — a person who interacts with the equipment only to the degree necessary for the equipment to

perform its intended function.

5.1.47 operator access — an area to which, under normal operating conditions, one of the following applies: access

may be gained without the use of a tool, the means of access is deliberately provided to the operator, or the operator

is instructed to enter regardless of whether or not a tool is needed to gain access (if the operator is so instructed, this

area becomes evaluatable as an operator accessible area).

5.1.48 overcurrent — any current in excess of the rated current of the equipment or the rated ampacity (current-

carrying capacity) of the conductor; it may result from overload, short circuit, or ground fault.

5.1.49 overload — operation of equipment in excess of normal, full-load rating, or of a conductor in excess of rated

ampacity that, when it persists for a sufficient length of time, would cause damage or dangerous overheating. A

fault, such as a short circuit or ground fault, is not an overload (see short circuit and ground fault).

SEMI S22-1103a © SEMI 2003, 2005 7

5.1.50 permanently connected equipment — equipment that is electrically connected to a supply by means of a

connection that may be detached only by the use of a tool.

5.1.51 pollution — any addition of foreign matter, solid, liquid or gas, that may produce a reduction of dielectric

strength or increase of surface resistivity.

5.1.52 pollution degree — for the purpose of evaluating clearances the following two degrees of pollution in the

micro-environment are recognized for use with this document:

5.1.52.1 pollution degree 1 — no pollution or only dry, non-conductive pollution occurs. The pollution has no

influence. Cleanroom Class 1000 or less.

NOTE 10: Cleanroom Class 1000 or less is pollution degree 1, however the pollution degree in a particular area in a given piece

of equipment may exceed pollution degree 1, even if the equipment is installed in a cleanroom class 1000 or less.

5.1.52.2 pollution degree 2 — normally only non-conductive pollution occurs. Occasionally, however, a temporary

conductivity caused by condensation is expected. Cleanroom Class greater than 1000.

NOTE 11: Cleanroom Class greater than 1000 is pollution degree 2, however the pollution degree in a particular area in a given

piece of equipment may exceed pollution degree 2, even if the equipment is installed in a cleanroom greater than 1000.

5.1.53 protective conductor — a conductor that provides electrical continuity between conductive components that

are not intended to be energized during normal operations and the equipment’s protective earthing conductor

terminal.

5.1.54 protective earthing conductor — a normally non-current carrying conductor connected between earth

(ground) at the source of supply and the protective earthing (grounding) terminal on the equipment enclosure.

5.1.55 protective earthing conductor terminal — a terminal bonded to conductive parts of an equipment enclosure

for safety purposes and intended to be connected to an external protective earthing (grounding) conductor (the

protective earthing conductor).

5.1.56 protective earthing system — the earthing (grounding & bonding) system connecting accessible conductive

parts of the equipment to an external earth (ground) at the source of supply. The protective earthing system may

include bonded structural members, bonding jumpers, the protective earthing conductor terminal on the equipment

and the protective earthing conductor in the incoming supply wiring to the equipment.

5.1.57 raceway — an enclosed channel of metal, or nonmetallic materials, designed expressly for holding wires,

cables, or busbars.

5.1.58 readily accessible — capable of being reached quickly for operation or inspection, without requiring

climbing over or removing obstacles or using portable ladders, chairs, etc.

5.1.59 reinforced insulation — a single layer of insulation that provides a degree of protection against electric shock

equivalent to double insulation.

5.1.60 risk — the expected losses from a mishap, expressed in terms of severity and likelihood.

5.1.61 safe shutdown condition — a condition in which all hazardous energy sources and hazardous production

materials are removed or suitably contained, unless this results in additional hazardous conditions.

5.1.62 safety circuit — a circuit whose intended function is to make the equipment safer. Interlocks, EMO circuits,

and other protective circuits are safety circuits.

5.1.63 service — unplanned activities intended to return equipment that has failed to proper working order (see also

maintenance).

5.1.64 severity — the extent of the worst credible loss (damage, injury, or release) from a mishap caused by a

specific hazard.

5.1.65 supplementary insulation — applied to basic insulation in order to ensure protection against electric shock in

the event of the failure of basic insulation.

5.1.66 testing — measurements or observations used to validate and document conformance to designated

criteria.

5.1.67 tool — an external device used to aid a person to perform a mechanical function.