Functionality - ABB REF615 Applications Manual

Section 5
Protection functions
5.5.2.2
5.5.2.3
168

Functionality

The three-phase undervoltage protection PHPTUV is used to disconnect devices from
the network, for example, electric motors which get damaged when subjected to
service under low voltage conditions. PHPTUV includes a settable value for the
detection of undervoltage either in a single phase, two phases or three phases.
PHPTUV includes both definite time (DT) and inverse definite minimum time
(IDMT) operate time characteristics for the delay of the trip.
The function contains a blocking functionality. It is possible to block function outputs,
timer or the function itself, if desired.
Application
PHPTUV is applied to power system elements, such as generators, transformers,
motors and power lines in order to detect low voltage conditions. Low voltage
conditions are caused by abnormal operation or a fault in the power system.
PHPTUV can be used in combination with overcurrent protections.
Other applications are the detection of a no-voltage condition, for example, before
the energization of a high voltage line or a automatic breaker trip in case of a blackout.
PHPTUV is also used to initiate voltage correction measures, such as insertion of
shunt capacitor banks to compensate reactive load and thereby to increase the voltage.
PHPTUV can be used to disconnect devices from the network, for example, electric
motors which get damaged when subjected to service under low voltage conditions.
PHPTUV deals with low voltage conditions at power system frequency. Low voltage
conditions may occur due to:
• malfunctioning of a voltage regulator or incorrect settings under manual control
(symmetrical voltage decrease)
• overload (symmetrical voltage decrease)
• short circuits, often as phase-to-earth faults (unsymmetrical voltage increase).
PHPTOV prevents sensitive equipment from running under conditions that could
cause overheating and thus shorten their life time expectancy.
In many cases, PHPTOV is a useful function in circuits for local or remote automation
processes in the power system.
1MRS756378 D
REF615
Application Manual