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Ten Years Experience of CCM
in the Dutch Telephone Network
J. A. Harriers and C. Scheurwater
In April this year, exactly ten years have passed since CCM (Controlled
Corrective Maintenance) was introduced into the Dutch network, to be precise
in Rotterdam. Two articles dealing with experiences from this were
published in this journal during 1968 1 and 1972 2 . Since then, this maintenance
system has been further developed and large-scale introduction of an
electronic traffic route tester will take place throughout the country.
In this article the authors will give a survey of the introduction of CCM in
the Netherlands and of the results obtained.
UDC 621.395.722:
658.581
LME 154
The activities necessary for maintenance
and supervision of automatic
telephone exchanges depend to a
great extent on the service quality that
it is considered economically justifiable
to offer the subscribers.
Based on data obtained locally and
from abroad the conclusion was reached
already at an early date, that it was
unnecessary to test the exchanges
periodically, which on the contrary
could cause additional faults. Therefore
in 1957 the Central Telephone
Branch introduced new instructions,
which were based on visual inspection.
The equipment was selected on a
random sampling basis and checked
by an experienced technical staff. Thus
it was indicated in which part of the
telephone plant irregularities were occuring.
Measures were then taken to
remove these irregularities and as
much as possible prevent that they
were repeated.
Special attention was of course also
paid to faults reported by the subscribers
as this is of utmost importance
to enable the administration to offer a
good service quality. The knowledge
thus gained has resulted in decreased
maintenance efforts and improved
service quality.
Statistical methods using data from the
traffic route tester TRT have also been
introduced.
As mentioned above pure CCM was
consequently introduced in Rotterdam
in 1966. The main principle of this
method implies that maintenance
should conform to the required functional
quality of the exchange. The
switchroom should be entered only
when the quality determining equipment
indicates the right time for this
or when complaints have come from
subscribers. However, older types of
Fig. 1
General maintenance organization tor
telephone exchanges in the Netherlands