Manual Close Command; Dynamic Cold Load Pickup - Siemens SIPROTEC 7UT613 series Manual

2 Functions
User-Specified
Curves
2.4.1.3

Manual Close Command

2.4.1.4

Dynamic Cold Load Pickup

158
When user-defined curves are utilized, the tripping curve may be defined point by
point. Up to 20 pairs of values (current, time) may be entered. With these values the
device approximates the characteristic by means of linear interpolation.
If required, the dropout characteristic can also be defined. For the functional descrip-
tion see „Dropout". If no user-configurable dropout characteristic is desired, dropout is
initiated when approx. 95 % of the pickup value is undershot; when a new pickup is
evoked, the timer starts again at zero.
When a circuit breaker is closed onto a faulted protective object, a high speed re-trip
by the breaker is often desired. The manual closing feature is designed to remove the
delay from one of the time overcurrent stages when the breaker is manually closed
onto a fault. The time delay is then bypassed via an impulse from the external control
switch. This pulse is prolonged by at least 300 ms. To enable the device to react prop-
erly on occurrence of a fault, address 2008A MANUAL CLOSE and/or address 2208A
3I0 MAN. CLOSE have to be set accordingly. Thus, the user determines for both
stages, the phase and the residual current stage, which pickup value is active with
which delay when the circuit breaker is closed manually.
Figure 2-71 Manual close processing (simplified)
Processing of the manual close command can be executed for each measuring loca-
tion or side. Manual close signal is also generated when an internal control command
is given to a breaker which is assigned to the same protection function as the time
overcurrent protection, in the Power System Data 1 (Subsection 2.1.4).
Strict attention must be paid that the manual close condition is derived from that circuit
breaker which feeds the object that is protected by the time overcurrent protection!
The breaker concerning the phase overcurrent protection may be different from that
for the zero sequence overcurrent protection, dependent of the assignment of these
protection functions.
With the dynamic cold load pickup feature, it is possible to dynamically increase the
pickup values of the time overcurrent protection stages when dynamic cold load over-
current conditions are anticipated, i.e. when consumers have increased power con-
sumption after a longer period of dead condition, e.g. in air conditioning systems,
heating systems, motors, etc. By allowing pickup values and the associated time
delays to increase dynamically, it is not necessary to incorporate cold load capability
in the normal settings.
This function of the dynamic cold load pickup conditions is common for all time over-
current stages and is explained in the section 2.6 „Dynamic Cold Load Pickup for Time
7UT613/63x Manual
C53000-G1176-C160-2