definite time delay. Thus, if only the inverse time delay is required, it is
of utmost importance to set the definite time delay for that stage to zero.
Operate time characteristic
Negative sequence time overcurrent protection for machines NS2PTOC (46I2)
provides two operating time delay characteristics for step 1:
• Definite time delay characteristic
• Inverse time delay characteristic
The desired operate time delay characteristic is selected by setting CurveType1 as follows:
• CurveType1 = Definite
• CurveType1 = Inverse
Step 2 always has a definite time delay characteristic. Definite time delay is
independent of the magnitude of the negative sequence current once the pickup value is
exceeded, while inverse time delay characteristic do depend on the magnitude of the
negative sequence current.
This means that inverse time delay is long for a small overcurrent and becomes
progressively shorter as the magnitude of the negative sequence current increases.
Inverse time delay characteristic of the NS2PTOC (46I2) function is represented in the
equation
, where the K1 setting is adjustable over the range of 1 – 99 seconds.
A typical inverse time overcurrent curve is shown in Figure
214.
Section 3 1MRK504116-UUS C
IED application
506
Application manual
To Next Page
Loading...
Need help?
General
