Toshiba GR200 Series Instruction Manual page 139

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Scheme logic

The SOTF-OC function provides signals to the TRC function: SOTFOC-OPT-A,-B,-C, SOTFOC-

TRIP, and SOTFOC-ARC-BLOCK. The SOTF-OC function issues a trip signal upon the

operation of the OCSOTF element if CBs are closed onto a fault when energizing a

transmission line following a period of non-operation. The criterion for the transmission line

being in the non-operation state are when (1) the CBs are open for more than 0.5 seconds and

(2) the undervoltage elements in the PROT COMMON function remain operated for more than

0.5 seconds. The TRIP and PROT COMMON functions are discussed separately. (See chapter

Relay application: Trip circuit and Protection common

Setting [OCSOTF] is provided to determine the SOTF threshold. Setting [OCSOTF-2fBlk]

is used to override the SOTF function when the SOTF-OC detects a second harmonic. If Block-

3P is set for the setting [OCSOTF-2fBlk], all of the OCSOTF elements are overridden when

second harmonic is present. Alternatively, if Block-PerP is set for the setting [OCSOTF-2fBlk],

each individual OCSOTF element of the SOTF function is overridden for second harmonic

currents. The detection of the second harmonic is determined by the function of the inrush

current detector (ICD). The ICD function is discussed separately. (See chapter

application: Inrush current detection function

The SOTF-OC function is active when On is set for the setting [SOTFOC-EN]. Setting

[SOTF-test] is used for the mandatory condition of cold load when testing. When wishing to

add another condition into the logic for the SOTF operation, the user can inject the signal using

PLC connection point "ADD.SOTF.EN".

6F2S1915 (0.46)

GRZ200 (Soft 031 & 032)