1MAC309294-MB F Section 10General function block featuresRER620 533Technical ManualUser-programmable delayed inverse resetThe user can define the delayed inverse reset time characteristics with the followingformula using the set Curve parameter D.(Equation 63)t[s] Reset time (in seconds)k setTime multiplierD setCurve parameter DI Measured currentI> setPickup value10.2.3 Inverse-timer freezingWhen the BLOCK input is active, the internal value of the time counter is frozen at thevalue of the moment just before the freezing. Freezing of the counter value is chosen whenthe user does not wish the counter value to count upwards or to be reset. This may be thecase, for example, when the inverse-time function of a relay needs to be blocked to enablethe definite-time operation of another relay for selectivity reasons, especially if differentrelaying techniques (old and modern relays) are applied.Activating the BLOCK input alone does not affect the operation of the PICKUP output. Itstill becomes active when the current exceeds the set Pickup value, and inactive when thecurrent falls below the set Pickup value and the set Reset delay time has expired.The delayed inverse-time reset is not available for IEC-type inverse timecurves.t s DIIk[ ] =>⎛⎝⎜ ⎞⎠⎟ −⎛⎝⎜⎜⎜⎜⎜⎞⎠⎟⎟⎟⎟⎟⋅21The selected blocking mode is “Freeze timer”.The activation of the BLOCK input also lengthens the minimum delay valueof the timer.
