ABB Remote I/O RIO600 Installation And Commissioning Manual page 98

Section 6
Commissioning
90
Functionality
The three-phase non-directional overcurrent fault detection function PHPTOC is used
as one-phase, two-phase or three-phase non-directional overcurrent and short circuit
fault detection. The function starts when the current exceeds the set limit. PHPTOC
operates with definite time characteristic, that is, the function operates after a
predefined operate time and resets immediately when the fault current disappears.
Operation principle
The Operation setting is used to enable or disable the function. The corresponding
parameter values are "On" and "Off".
The operation of PHPTOC can be described by using a module diagram. All modules
in the diagram are explained in the next sections.
I_A
I_B
detector
I_C
GUID-0E8F13CC-F8FE-41CB-AF8D-7A4EA91B7C6B V1 EN
Figure 52: Functional module diagram
Level detector
The fundamental component of phase currents is compared phase-wise with the Start
value setting. If the measured value exceeds the Start value setting, the Level detector
reports the exceeding value to the phase selection logic.
The Absolute hysteresis setting can be used for preventing unnecessary oscillations in
the START and OPERATE output signals, if the input current is slightly above or
below the Start value setting. After leaving the hysteresis area, the start condition has
to be met again and if it is not sufficient, the signal returns to the hysteresis area.
Phase selection logic
If the fault criteria are fulfilled in the Level detector, the phase selection logic detects
the phase or phases in which the measured current exceeds the setting. If the phase
information matches the No. of start phases setting, the phase selection logic activates
the timer module.
Timer
Once the Timer is activated, it activates the STR GENERAL output. The STR PHSA,
STR PHSB and STR PHSC outputs indicate which phases are started. The time
characteristic is according to the Definite time. When the operation timer has reached
the value set by Operate delay time, the OP GENERAL output signal is activated. The
OP PHSA, OP PHSB and OP PHSC outputs indicate which phases are operated. If
the fault disappears before the module operates, the reset is instantaneous and STR
GENERAL is deactivated.
Phase
Level
selection
logic
1MRS757488 H
Op general
Timer
Op phsA
t
Op phsB
Op phsC
Str general
Str phsA
Str phsB
Str phsC
Installation and Commissioning Manual
RIO600