Ampcontrol Pty Ltd
– ABN 28 000 915 542
ELV-PRO USER MANUAL
MAG-219 Version 5
– NOVEMBER/2020
Uncontrolled Copy - Refer to Ampcontrol Website for Latest Version
Page 17 of 59
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4.4.3 Earth Leakage CT, CT Test, Zero Crossing Input Connections (Plug 6)
The Earth Leakage protection is achieved through the use of a core balance CT. The connections to
the CT are terminals P6_1 & P6_2. Terminal P6_3 is the screen termination point for the cable
connecting the EL CT to the relay. For further details see Section 4.4.9.
NOTE
The loop impedance of the cables used to connect the EL CT to
the ELV-PRO relay must be less than 1
Ω.
It is recommended that this
is wired as a twisted pair shielded cable.
To ensure the CT is connected and the signal the relay monitors is correct, a CT test output is provided
on terminals P6_5 & P6_6. A missing CT Test signal through the CT will cause the ELV-PRO relay to
trip. The test signal is applied every two seconds, and may be seen on the live screens and data logs.
Terminal P6_4 of Plug 6 should not be connected.
The Zero Crossing input, terminals P6_7 & P6_8, is provided for logging purposes.
ELV-PRO
NER
Alternate
Installation
To neutral of Star
Connected Transformer
P6_6
P6_3
P6_2
P6_1
P6_5
P6_4
CT TEST
EL CT SCRN
EL CT
EL CT
SIGNAL
DO NOT
CONNECT
Plug 6
ZERO CROSSING
INPUT (110VAC)
Zero Crossing
Detector
P6_8
P6_7
Figure 4-6: Electrical Connections
– EL CT, CT Test and Zero Crossing Connections (Plug 6)
NOTE
The protection system constantly injects a CT test signal into the CT
every two seconds. As such, the earth leakage graph will record a small
non-zero value, even when the outlet is open (Not connected to the
load). This confirms that the Earth Leakage system is operational.