ABB REO 517, Applications Manual, Page: 144 / 440

134
Unbalance protection for capacitor banks
(TOCC)
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The function is disabled (blocked) if:
• The terminal is in TEST mode (TEST-ACTIVE is high) and the function has been
blocked from the HMI (BlockTOCC=Yes).
• The input signal TOCC--BLOCK is high.
The TOCC-BLOCK signal can be connected to a binary input of the terminal in order
to receive a block command from external devices or can be software connected to other
internal functions of the terminal itself in order to receive a block command from inter-
nal function. Through an OR gate it can be connected to both binarey inputs and internal
function outputs.
The low current and high current signals can also be blocked individually by the settings
Operation Low = Off and Operation High = Off.
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The parameters for the unbalance protection for capacitor banks function are set via the
local HMI or PST (Parameter Setting Tool). Refer to the Technical reference manual
for setting parameters and path in local HMI.
The current stage I>High is normally set to trip the capacitor battery before any unit
is subjected to a voltage increase of 10% above rated value. The delay tHigh should be
set longer than the operate time of the earth fault protection if the primary operate cur-
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TEST-ACTIVE
BlockTOCC = Y es
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TEST
TOCC-BLOCK
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& TOCC-TRLS
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≥
1
tLow
tHigh
TOCC-TRHS
Lo w
I >
High