P92x/EN FT/E11 Technical Guide
User Guide
Page 40/110 MiCOM P921-P922-P923
10.1 Undervoltage protection
10.1.1 Description
This function can be configured according to the connection scheme of the VTs :
phase-phase protection (delta connection) or phase-neutral protection (star
connection).
The configuration of this function can also be done in order to detect an absence of
voltage for all phases :
· Undervoltage condition for one of the 3 phases (select OR for the considered
stage),
· Undervoltage condition for all 3 phases (select AND for the considered stage).
The settings of the voltage thresholds are done in secondary values.
The relay will trip according to an inverse characteristic or a definite time
characteristic for the first stage and according to a definite time characteristic for the
second and third stages.
The inverse characteristic is given by the following formula :
t = K / ( 1-M )
Where, K = Time Multiplier Setting
t = operating time in seconds
M = Applied input voltage / Relay setting voltage (Vs).
10.1.2 HMI description
To gain access to the “UNDERVOLTAGE” sub-menu from the default display, press
2 once, 6 4 times and 2 once.
[27] UNDERVOLTAGE
Heading of the undervoltage sub-menu.
[27] V<=
NO
Description : configuration of the first undervoltage stage
Range : NO / AND / OR
Note : if disabled (« NO » selected), all the following messages
are invisible, until « V<< » message.
[27] V<=
5.0 V
Description : setting of the first undervoltage stage
Range : range 57-130V : 5-130V step = 0.1V
range 220-480V : 20-480V step = 0.5V
[27] DELAY TYPE =
DMT
Description : selection of the time delay characteristic
Range : definite time (DMT) / inverse definite time (IDMT)
[27] TMS=
1.0
Description : time multiplier setting.
Range : 0.5 – 100, step = 0.5
Note : this message only seen if “IDMT” time delay selected
[27] tRESET V<=
10 ms
Description : reset time for the first undervoltage stage
Range : 0 – 100s, step = 0.01s
Note : this message only seen if “IDMT” time delay selected
To Next Page
Loading...
