Under/Over Voltage ProtectionFor automatic circuit reclosers with PTCC controllers

Under/Over Voltage Protection

Under/over Voltage Protection can be configured to cause the recloser to trip, if the measured system voltage goes outside preset limits for a preset time.

The recloser uses logic based on ‘AND’, ‘OR’ or ‘AVERAGE’ evaluation to determine if the system voltage maintains a ‘normal voltage’ state.

A recloser can be configured to automatically reclose after an under or over voltage protection trip, if the system voltage has returned to an acceptable value.

Voltage Protection can also be configured to:

Force ‘voltage protection’ off in the case of excessive voltage protection sequences.

Force ‘normal voltage close’ off in the case of a voltage protection recovery timeout.

Under/Over Voltage Protection Capability

Accessing Under/Over Voltage Protection settings via WSOS

Making Under/Over Voltage Protection Available via WSOS

Launching the Under/Over Voltage Protection Setting Screen via WSOS

Over Voltage Protection Timing

VOLTAGE

tSwitchgear Status

6300V

7560V

6930V

Over Voltage Pickup

Over Voltage Reset 7434V

Over Voltage Normal Over Voltage Normal Reset 7056V

CLOSEDOPENCLOSED

Over Voltage Pickup at this time

Over Voltage Reset at this time

Over Voltage Trip Delay Timer

Trip at this time

Normal Voltage Close Time

Close at this time

Under and Over Voltage Phase Logic

Under and Over Voltage Phase Logic Options

Phase Logic controls the method in which measured voltages are evaluated against the under/over Voltage Threshold.

The Options are:

AND All measured phase voltages must deviate beyond the

Pickup Threshold for pickup to occur. OR

Any measured phase voltage which deviates beyond the Pickup Threshold will cause pickup to occur.

AVERAGE The numerical average of all three measured phase

voltages must deviate beyond the Pickup Threshold for pickup to occur.

Normal Voltage Close

Normal Voltage Close Events

Normal Voltage Close ON/OFF

Normal Voltage Close ON enables the controllers normal voltage close functionality which causes the ACR to automatically close when:

The most recent trip was a UOV protection trip, The switchgear source side voltages have returned to a

‘Normal Voltage’ state, ‘Normal Voltage Close’ was ON before the UOV trip and is still

ON,

AND

The ‘Normal Voltage’ state has persisted for the duration of the Normal Voltage Close Delay time period.

Voltage Protection Recovery Timeout

Voltage Protection Recovery Timeout Operation

If Normal Voltage Close is ON

and the switchgear does not

‘Normal Voltage Close’

subsequent to a

‘UOV Protection Trip’

in less than or equal to the

‘Normal Recovery’ period

then:

‘Normal Voltage Close’ will be forced OFF

And

The Switchgear will go to ‘Lockout’

Range 0 – 1000s

Setting Recovery Time Out to

Off

Will inhibit this feature

Excess UOV Protection Sequences

Excess UOV Protection Sequences

If the number of Voltage Protection sequences equals the

‘excess sequence’ count threshold

within the voltage sequence count accumulation period then:

Under Voltage Trip

Over Voltage Trip

Normal Voltage Close …….. Will all be forced OFF

Single Sided CVT Switchgear

If UOV Protection is Available on the controller

and the attached switchgear is only fitted with CVT’s on one side

and if the controllers Source/Load designation is set such that the designated Load side has the CVT’s fitted

Then UOV Protection ‘Normal Voltage Close’ will be forced to OFF

and if the switchgear is in a UOV Protection tripped state,

Then the switchgear will go to Lockout.

Protection Menu Navigation

6x Earth Protection Settings

6x NPS Protection Settings

3x Global Protection Settings

2x Protection Features Settings

2x Frequency Protection Settings

6x Phase Protection Settings

3x Under/Over Voltage Settings

UOV Protection OCPM Screens

Questions?

On which screen can Under/Over Voltage Protection be made available via the OCPM? Options 3 in the System Status menu.

With UOV Phase Logic set to ‘Average’, what voltage value will the protection use for A = 0V B = 15000V C = 16000V? 15500V

At which voltage will the Normal Voltage Close timer start following an Over Voltage trip with the following settings?Over Voltage trip at: 15000VOver Voltage normal at: 14000VNominal Phase to Earth 12600V 14000V

How many UOV Protection screens are on the OCPM and where? Three screens at the end of the Protection menu.