Page 8-7
IL17569
Effective June, 2001
Table 8.2 Negative Sequence Current Protection Settings
Parameter Range Step
46-1 IUB 0.10 to 20 pu, 0.01 pu
Threshold Disabled
46-1 IUB % 4% to 40% 1%
Unbalance
46-1 IUB 0 to 9999 Cycles 1 Cycle
Delay
46-2 IUB 0.10 to 20 pu, 0.01 pu
Threshold Disabled
46-2 IUB % 4% to 40% 1%
Unbalance
46-2 IUB 0 to 9999 Cycles 1 Cycle
Delay
8.4 Curve Overlapping Issues
Several calculations are performed simultaneously for the determi-
nation of trip and alarm conditions. Each of these trip and alarm
criteria are considered independently of each other. Whichever
condition occurs first will cause the fault with no additional coordina-
tion between the processes.
8.5 Zone Interlocking Behavior and Application
To minimize damage to the system, faults should be cleared as
quickly as possible. Zone interlocking provides this capability better
than a system with only selective coordination. Zone interlocking
functions must be programmed (see Section 5.5.2.9) before they
can be used. By default the function is disabled.
The zone interlocking protection scheme provides a way for
a protective device to determine if a device, in a downstream
zone, picks up a fault and is taking action. With this information,
the protective device can immediately trip if no other device is
taking action or use its programmed time delay if another device
is taking action.
8.5.1 Compatible Zone Interlock Devices
The Cutler-Hammer FP-5000 and DT-3000 protective relays support
the zone interlocking function and are compatible with each other.
Refer to the DT-3000 instruction book (I.B. 17555) for details on the
DT-3000 implementation of the zone interlocking function.
8.5.2 Connection Rules
Zone interlocking information is passed on a two-wire Twisted pair
communication pair, see Section 6.11, for complete wiring details.
All devices in the same zone wire their zone-out terminals (J3-1 and
J3-2) in parallel see Figure 8-10. Zone Interlocking Example with
FP-5000 and DT-3000. This daisy chained wire pair is then
connected to the upstream zone protection device zone-in terminal
(J3-4 and J3-2). Up to 10 devices can have their zone-out terminals
wired in parallel. Only one device, in the upstream zone should have
these wires connected to its zone-in terminals.
Any downstream device can drive the daisy chained wire pair active,
signaling that the device is going to take action. In this case the
upstream device will not trip immediately but will use the pro-
grammed time delay.
8.5.3 Operation (see Figure 8-10).
In general, if configured, the zone-out signal in a FP-5000 is driven
when the protective device is picked up on an Instantaneous Over
Current (IOC) or Inverse Time Over Current (TOC).
In particular, if the Zone Out setpoint is “Phase” then any
phase current IOC or TOC pickup will activate the zone out signal.
Ground or residual current IOC or TOC will not activate the signal.
If the Zone Out setpoint is “Ground” then any ground or residual
current IOC or TOC will cause activation of zone-out signal. Phase
current IOC or TOC will not activate the signal.
If the Zone Out setpoint is “Both” then phase, ground and residual
currents over the IOC or TOC pickup levels will cause the zone-out
signal to activate.
If the Zone Out setpoint is set to “Disable” then the zone-out signal
will not activate.
To Next Page
Loading...
