ABB RELION REX640 Technical Manual page 868

Protection and control

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Protection functions

Operation principle

The function can be enabled and disabled with the

corresponding parameter values are "On" and "Off".

The operation of ROVPTOV can be described by using a module diagram. All the

modules in the diagram are explained in the next sections.

Figure 487: Functional module diagram

Level detector

The residual voltage is compared to the set

Start value , the level detector sends an enable signal to the timer.

Once activated, the timer activates the START output. The time characteristic is

according to DT. When the operation timer has reached the value set by

delay time , the OPERATE output is activated. If the fault disappears before the

module operates, the reset timer is activated. If the reset timer reaches the

value set by

deactivated.

The timer calculates the start duration value START_DUR, which indicates the

percentage ratio of the start situation and the set operation time. The value is

available in the monitored data view.

Blocking logic

There are three operation modes in the blocking function. The operation modes

are controlled by the BLOCK input and the global setting in Configuration >

System > Blocking mode which selects the blocking mode. The BLOCK input can

be controlled by a binary input, a horizontal communication input or an internal

signal of the protection relay's program. The influence of the BLOCK signal activation

is preselected with the global setting

mode, the operation timer is frozen to the prevailing value, but the OPERATE output

is not deactivated when blocking is activated. In the "Block all" mode, the whole

function is blocked and the timers are reset. In the "Block OPERATE output" mode,

the function operates normally but the OPERATE output is not activated.

Reset delay time , the operate timer resets and the START output is

Blocking mode setting has three blocking methods. In the "Freeze timers"

Start value . If the value exceeds the set

Blocking mode .

1MRS759142 F

Operation setting. The

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