Electricity + Control April 2015

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Three phase general motor and
pump protection
NewElec designs, manufactures and markets three-phase mo-
tor protection relays. However, some of its relays are geared
towards specific applications, such as pump protection. The
NewElec development team has worked with experts in the
pumping industry to develop relays much more suited to the
application.
As an example, the dry run protection (or minimum load
or load loss) helps to trip the pump when there is no more
media to pump.This is important to safeguard the pump from
cavitation thus damaging the pump’s impeller.The settings for
dry run are percent-
age load level where
the pump is known
to be running dry and
associated time re-
quired to confirm the
condition. This per-
centage load level is
obtained by testing
and using empirical
data for the specific
pump, whereas time
delay is typically set to 10 s or operating specification. Ad-
ditionally, one needs to determine when the pump can restart
and continue to pump.This can either be calculated based on
the pumping infrastructure, for instance dam or sump level,
or trial and error.
All these parameters can be easily set on NewElec’s KD/KE or
NewCode relays, which are geared for pumping environments
amongst other applications.
. 012 327 1729 or email
ELECTRICAL PROTECTION + SAFETY
Increase your energy efficiency
The first rolling blackouts (commonly called load shedding) of
2007/8 shook the country and started discussions around en-
ergy efficiency. It appears 2015 is going to be worse. Since the
beginning of 2015 there have been constant power disruptions
throughout the country. Everyone has been asked to conserve
electricity and save up to 15 %.
However, one cannot control what is not measured.This is
where NewElec’s range of electronic motor protection relays
comes in (such as the NewCode motor protection and control
relay), as it has the ability to measure electrical energy con-
sumption. This totalised energy consumption
(real watt-hours and var-hours) information
can now be downloaded into process
databases for further analysis. In ad-
dition to comprehensive consump-
tion knowledge, wheremotors are
found to be overrated, they can
be replaced with smaller more
efficient motors, reducing opera-
tional costs.
. 012 327 1729 or email