Table 6.1.2.-5
Current and voltage sensor input values
Voltage at rated current I
n
150 mV (rms)
Voltage at rated voltage U
n
2 V (rms)
Rated frequency f
n
50 Hz or 60 Hz
6.1.3.
Analog input modules
Several different types of analog input modules are available to manage the different
protection functions.
The modules are equipped with the following combinations of input current and/or
voltage transformers:
*
3 or 6 current transformers for phase currents
*
3 or 6 voltage transformers for phase-to-ground or phase-to-phase voltages
*
1 or 2 current transformers for residual currents
*
1 or 2 voltage transformers for residual voltages
There are also versions for sensor inputs and mixed ones, to connect both
conventional instrument transformers and sensors. At most, eight input channels are
available. If programmed, input channels can be supervised.
The first three analog input channels (1-3) are designed for connecting current
transformers and the next three channels (4-6) for connecting voltage transformers.
The last two channels (7 and 8) are designed for measuring the residual current and
residual voltage.
The power flows can still be calculated, if six current transformers, for example in
case of transformer differential protection, are connected and the related line
voltages of the network are connected to the last two analog input channels. The
analog input channels 1 and 3 must be connected to the current transformers of
NET1. The last two input channels 7 and 8 must be connected to the line voltages of
NET1. If required, the power flow calculation can be done in the bus tie part of the
switchgear, where six voltage transformers are connected to the analog input
channels 1-6. The analog input channels 4 and 6 must be connected to the phase
voltage of NET1. The last two input channels 7 and 8 must be connected to the
current transformer of NET1.
6.1.4.
Reaction time
In this context the protection reaction time is defined as the time elapsed between
the fault detection and the closing of the contact that gives supply to the circuit-
breaker tripping coil (or the equivalent tripping mechanism for magnetic drive or
contactors). This time is the sum of different intervals:
1. Fault detection time
2. User defined pre set delay (for definite time protection functions)
3. Trip information processing
4. Relay output contact actuation
38
REF 542plus
REF 542plus
Multifunction Protection and Switchbay Control
Unit
Technical Reference Manual
1MRS755859