Assessment Of Risk Components - Furuno WR2120 Installation Manual

A.2.2. Assessment of Risk Components
Each risk component ��
following general equation:
where
is the number of dangerous events per annum
��
��
is the probability of damage to a structure
��
��
is the consequent loss
��
��
The number ��
physical characteristics of the structure to be protected, its surroundings, connected lines and the
soil.
The probability of damage ��
connected lines and the protection measures provided.
The consequent loss ��
persons, the type of service provided to public, the value of goods affected by the damage and the
measures provided to limit the amount of loss.
Composition of risk components:
Composition of each risk components are as follows:
: Risk of loss of service to the public: ��
��
2
: Risk of loss of economic values:
��
4
I. Risk components for a structure due to flashes to the structure
: Component related to physical damage caused by dangerous sparking inside the structure
��
��
triggering fire or explosion which will also endanger the environment. All types of loss (L1, L2,
L3 and L4) will arise.
: Component related to failure of internal systems caused by lightning electromagnetic
��
��
impulse (LEMP). Loss of type L2 and L4 could occur in all cases along with type L1 in the case
of structures with risk of explosion, and hospitals or other structures where failure of internal
systems immediately endanger human life.
: Component related to failure of internal systems caused by LEMP. Loss of type L2 and L4
��
��
could occur in all cases, along with type L1 in the case of structures with risk of explosion, and
hospitals or other structures where failure of internal systems immediately endangers human
life.
II. Risk components for a structure due to flashes to a line connected to the structure
: Component related to injury to living beings caused by electric shock due to touch voltage
��
��
inside the structure. Loss of type L1 and, in the case of agricultural properties, loss of type L4
with possible loss of animals could also occur.
: Component related to physical damage (fire or explosion triggered by dangerous sparking
��
��
between external installation and metallic parts generally at the entrance point of the line into
the structure) due to lightning current transmitted through or along incoming lines. All types of
loss (L1, L2, L3 and L4) will occur.
: Component related to failure of internal systems caused by overvoltages induced on
��
��
incoming lines and transmitted to the structure. Loss of type L2 and L4 could occur in all cases,
along with type L1 in the case of structures with risk of explosion, and hospitals or other
structures where failure of internal systems immediately endangers human life.
III. Risk components for a structure due to flashes near a line connected to the structure
: Component related to failure of internal systems caused by overvoltage induced on
��
��
incoming lines and transmitted to the structure. Loss of type L2 and L4 could occur in all cases,
along with type L1 in the case of structures with risk of explosion, and hospitals or other
structures where failure of internal systems immediately endanger human life.
, �� �� , �� , ��
�� ��, �� ��
of dangerous events is affected by lightning ground flash density (��
��
is affected by characteristics of the structure to be protected, the
��
is affected by the use to which the structure is assigned, the attendance of
��
, and �� , consists ��
�� ��
�� = �� × �� × ��
�� �� �� ��
= �� + �� + ��
2 ��2 ��2
�� = �� + �� + ��
4 ��4 ��4
53
and �� may be expressed by the
2 4
+ �� + �� + ��
��2 ��2 ��2 ��2
+ �� + �� + ��
��4 ��4 ��4 ��4
) and by the
��