Application Guide - NP900 Series
361 (504
)
A996A
3.5.3.1
T
HERMAL OVERLOAD FUNCTION
IO
Blocking signal and setting group selection controls the operating characteristics of the
function during normal operation.
Outputs of the function are TOLT Trip and Blocked signals. Setting parameters are static
inputs for the function which are changed only by user input in the setup phase of the
function. TOLT function utilizes total of eight separate setting groups which can be
selected from one common source. Also the operating mode of the TOLT can be changed
by setting group selection.
The operational logic consists of input magnitude processing, thermal replica, comparator,
block signal check and output processing.
Inputs for the function are setting parameters and measured and pre-processed current
magnitudes. Function output signals can be used for direct IO controlling and also for user
logic programming. The function registers its operation into 12 last time-stamped registers
and also generates general time stamped ON/OFF events to the common event buffer
from each of the two output signal. Time stamp resolution is 1ms. Function provides also
cumulative counters for TOLT Trip, Alarm 1, Alarm 2, Inhibit and BLOCKED events.
In the following figure is presented the simplified function block diagram of the TOLT
function.
Figure 3.5.3.1-171 Simplified function block diagram of the TOLT function.
