Toshiba GRZ100 B Series, Instruction Manual

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2.4.16 Fault Detector
GRZ100 model 400s and 500s are provided with a fault detector (FD) which functions as a check
relay and enhances security, or prevents false tripping due to a single failure in the protection
system.
The FD is an independent module and incorporates the following six fault detection elements. The
FD output signal is an ORing of the elements output signals shown in Figure 2.4.16.1.
•
Current change detection element (OCDF)
•
Multi-level overcurrent element (OCMF)
•
Earth fault overcurrent element (EFF)
•
Undervoltage element for earth fault detection (UVGF)
•
Undervoltage element for phase fault detection (UVSF)
•
Undervoltage change detection element (UVDF)
Figure 2.4.16.1 Fault Detector Logic
The FD output signal drives two sets of high-speed checking output relays. The checking output
relay resets 60ms(*) after the fault detection elements are reset by clearing the fault.
(*) Reset time is adjustable by PLC function. Default setting is 60ms.
The OCDF operates in response to load current if it is a steeply fluctuating one. When the relay is
used for a line with such a load current, the OCDF can be disabled by short-circuiting dedicated
paired pins on the module with a receptacle.
All the FD elements have fixed operating threshold levels. But if the earth fault current due to
unbalance in the network is significant, the EFF can be desensitized in the same way as described
above.
Note:
To give high independency to the module, the human machine interface on the front panel or
PC has no access to the FD module except for the user configurable binary output relays
mounted on it.
When it is desirable to disable the OCMF, disable the OCDF or desensitize the EFF, take the
following steps:
•
Pull out the FD module. For a description of how the module is removed, refer to Section6.7.3.
•
Four pairs of pins J1 and J2 are arranged lengthwise on the front at the top of the module as
shown in Figure 2.4.16.2.
J2:3-4
&
&
+
≥
1
&
≥
1
0.06s
t 0
0.06s
t 0
FD1
FD2
OCMF
EFF
OCDF
UVDF
UVSF
UVGF