Ampcontrol IPD - Current Related Functions; General Information

Ampcontrol Pty Ltd – ABN 28 000 915 542
IPD USER MANUAL
IPDB014 Version 14 – SEP/2020
Uncontrolled Copy - Refer to Ampcontrol Website for Latest Version
Page 45 of 96
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– NOT TO BE REPRODUCED IN PART
10 CURRENT RELATED FUNCTIONS
10.1 General Information
The IPD relay uses two current transformers to measure the three line currents. The measured currents
are used to implement the following protection functions:
 Time Dependent Protection, including:
o Over-Current Protection
o Motor Overload Protection
 Short Circuit Protection
 Phase Current Balance
In addition to the above functions, IPD relays from Version 3 onwards have also had a Transient
Overreach Compensation function implemented to compensate for spurious tripping from overreach at
start-up. The IPD has a transient overreach performance figure of 35% (determined per IEC 60255-151,
section 6.5.2). See Section 10.5 for more information.
Figure 10.1: Current Transformer Circuit Terminations
10.1.1 Full Load Current Parameter
Full load settings cover a range from 7.5 Amps to 464 Amps. A current range and current multiplier are
utilised to select and store the full load current value in the non-volatile memory. This forms the basic
reference level for the over-current protection functions.
The current range is selectable in 4 Amp increments between 60 and 116 Amps. The current multiplier
is selectable at 1/8, 1/4, 1/2, 1, 2, 4 times (see Section 13, User Adjustable Settings).
NOTE
Example: Full Load Current Setting
To obtain a full load current of 152 Amps; select a current range of 76
Amps and a multiplier of 2.
A B C
Phase Conductors
Current TXF
1000/1
Current TXF
1000/1
IPD
Relay
Ic1
17
Ia1
15
Ic2
16
18
Ia2
S1
S2
P1
P2
S1
S2
P1
P2