N U M E R I C A L O C / E F P R O T E C T I O N R E L AY AD R 1 4 1 C / 2 4 1 C
ASHIDA Electronics Pvt. Ltd.
Ref: Manual / ADR141C / 241C
Issue: 04D
Date : 10.07.2014
Page
11/86
4.5
Cold Load pickup:-
When the Circuit breaker is closed on load, A load current take sudden inrush current. This
inrush current may be more than 4 to 5 times of rated load current. The duration can be as
high as 200ms. Due to this inrush current many times relay operates which is undesirable.
General practice is to keep normal setting to such high value so that it will not mal operate at
initial closing which result increase in fault clearance time. To avoid such problem relay is
equipped with special features known as
cold load pickup
.
Whenever a circuit breaker is
turn on relay sense through CB auxiliary contact and start internal timer known as CL timer.
During this time it takes separate set of setting, so that relay will not mal operate on inrush
current
5. Construction
Details
The relay is designed in flush mounting cabinet. The overall size of cabinet is 138 x 114 x
175mm Ref. diagram MAC01501.
6.
Self Check Feature
The DSP used in relay is having major of it component are within the chip. The controller
check all the components which are outside of chip such as ADC, Non volatile memory used
for disturbance data, and event, non volatile memory used for relay setting, real time clock
etc. Relay checks its internal hardware after every hardware-reset press and periodically
ones per day. If any fault in hardware is detected the relay change contact marked as
PROTH and display error code on LCD display. Depend upon the component relay take
necessary action.
Following table summarized the type of fault and action taken by relay
Type of Fault
(Error code)
Action
ADC Error
16
Most critical Error. Relay give error message and change
PROTH contact
Relay use alternate ADC for OCR section
and OCR remain in protection
NV RAM used for
disturbance record
32 & 64
Generate Error signal and remain in protection change
PROTH contact
NV RAM use for
setting 2
Generate Error signal and remain in protection by
assuming
default setting value. change PROTH contact
Setting Error 1
Generate Error signal and remain in protection by
assuming
default setting value. change PROTH contact
RTC Error
4 & 8
Generate Error signal and remain in protection change
PROTH contact
Trip Ckt Supervision
Fail Error 128
Generate Error signal and remain in protection by
assuming
default setting value. change PROTH contact
