Victron VM-3P5A Energy Meter Manual 3. Installation 3.1. Installing and wiring external current transformers (CTs) The VM-3P5A requires external current transformers (CTs) for current measurement. CTs are not included and must be sourced separately. Victron Energy does not supply CTs for the VM-3P5A. CT requirements Use CTs with a 5 A secondary output The CT primary current setting in the VM-3P5A must match the CT rating. For example, a CT marked 100/5 A must be configured as 100 A primary current. See Configuration & Monitoring [8] for details on how to configure the primary current. Connect the CT secondary terminals as follows: Wiring the CTs Ensure the polarity is correct on all phases.
Reversed polarity will result in incorrect power and energy readings. CT orientation If the CT is marked with a direction arrow or polarity indicator, install it with the marking pointing from the AC source towards the loads. For CTs with S1/S2 polarity markings, S1 should face the AC source side and S2 the load side. Important notes Use one CT per phase and connect each CT to the corresponding input terminal (CT-1, CT-2, CT-3). Ensure the phase voltage inputs and CTs correspond to the same phase. Do not install CTs on bare conductors. Follow the CT manufacturer’s installation instructions to avoid damaging the transformer. CT extension cables may increase measurement noise.
To minimise induced noise, use twisted pair wiring. Page 4 Installation • S1 / + → CT-[1..3] left terminal of the connector (top view) • S2 / – → CT-[1..3] right terminal of the connector (top view) S1S2 S1S2 S1S2