ABB RELION 670 SERIES REG670 - Operate Time Characteristic

definite time delay. Thus, if only the inverse time delay is required, it is
important to set the definite time delay for that stage to zero.
9.12.3.1 Operate time characteristic
GUID-0F3D5C8B-B485-4FEC-8448-CEAA1F6710D6 v6
Negative sequence time overcurrent protection for machines NS2PTOC
(46I2)
provides two operating time delay characteristics for step 1 and 2:
• 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
Definite time delay
[1]
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
2
2
I t K=
, where the K1 setting is adjustable over the range of 1 – 99 seconds.
A typical inverse time overcurrent curve is shown in Figure 202.
[1] The definite time delay is described by the setting t1, which is the time between activation of pickup and trip outputs.
Section 9 1MRK 502 071-UUS A
Current protection
422 Generator protection REG670 2.2 ANSI and Injection equipment REX060, REX061, REX062
Application manual