ABB RELION REX640, Техническое руководство, Страница: 863 / 1960

by a binary input, a horizontal communication input or an internal signal of the
protection relay's program. The influence of the
BLOCK
input signal activation is
preselected with the global
Blocking mode setting.
The
Blocking mode setting has three blocking methods. In the "Freeze timers"
mode, the operation timer is frozen to the prevailing value, but the
OPERATE
output
is not deactivated when blocking is activated. In the "Block all" mode, the whole
function is blocked and the Timers are reset. In the "Block OPERATE output" mode,
the function operates normally but the
OPERATE
output is not activated.
The “Freeze timers” mode of blocking has no effect during the “Inverse
reset” mode.
4.5.2.6 Timer characteristics
The operating curve types supported by PHPTUV are:
Table 793: Supported IDMT operate curve types
Operating curve type
(5) ANSI Def. Time
(15) IEC Def. Time
(21) Inv. Curve A
(22) Inv. Curve B
(23) Programmable
4.5.2.7 Application
PHPTUV is applied to power system elements, such as generators, transformers,
motors and power lines, 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 an 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 for a reactive load and thereby to increase the voltage.
PHPTUV can be used to disconnect from the network devices, such as electric
motors, which are damaged when subjected to service under low voltage
conditions. PHPTUV deals with low voltage conditions at power system frequency.
Low voltage conditions can be caused by:
• 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).
PHPTUV prevents sensitive equipment from running under conditions that could
cause overheating and thus shorten their life time expectancy. In many cases,
PHPTUV is a useful function in circuits for local or remote automation processes
in the power system.
1MRS759142 F Protection functions
REX640
Technical Manual
863