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Isolation Transformer

3. Installation

In this section:

3.1. What's in the box

The isolation transformer ships with the following items:

Description

1x hanging bracket, used for mounting the isolation transformer inside a vessel.

1x isolation transformer.

1x long yellow/green wire with eye terminals, used for case grounding.

1x short yellow/green jumper wire with female 6.35 mm spade connectors, used to connect AC input earth (PE) to AC output earth (PE) when the vessel is out of the water for maintenance or winter storage.

1x short yellow/green jumper wire with female 6.35 mm spade connectors, used to make AC output neutral (N) to earth (PE) link.

4x short black jumper wires with 6.35 mm female spade connectors, used for AC configuration.

7x mounting screws.

3.2. Connections overview

Isolation_transformer_-_Connections_7000.png

ID

Description

1

AC input screw terminals (shore power):

Phase (L) neutral (N) and earth (PE).

2

Male spade terminals to establish an AC output neutral to earth connection link for a correct operation of an AC output CFCI:

J5 and J7.

3

AC output screw terminals for the AC loads or AC installation on the vessel:

Phase (L) neutral (N) and earth (PE).

4

Male spade terminals to bridge AC input earth to AC output earth when the vessel is out of the water:

J9 and J12.

Note

The Earth link wires used in points 2 and 4 are included with the transformer. They have a core surface area of 6mm² (10AWG) and are connected to a 6.3mm spade terminal. Depending on local electrical regulations, this cable surface area might not be large enough to carry the potential fault currents of the AC system where the isolation transformer is used. If wires with a larger core surface area are required, then do not use the jumper connections but make the connections between the AC input and/or AC output terminal instead. Alternatively, make these connections external from the isolation transformer.

3.3. Connecting AC input and AC output

Warning

Shock hazard. Do not work on the isolation transformer or the electrical system if still connected to an electrical power source.

Connection sequence:

  1. Pass the AC cables through the cable glands at the bottom of the cabinet in the following way:

    1. Pass the AC input (shore power) cable through the left side cable gland.

    2. Pass the AC output (AC loads) cable through the right side cable gland.

  2. Connect the AC input cable to the INPUT terminal block in the following way:

    1. Connect the earth wire to the PE terminal.

    2. Connect the neutral wire to the N terminal.

    3. Connect the phase wire to the L terminal.

  3. Connect the AC output cable to the OUTPUT terminal block in the following way:

    1. Connect the earth wire to the PE terminal.

    2. Connect the neutral wire to the N terminal.

    3. Connect the phase wire to the L terminal.

  4. Connect the enclosure to the ground (=all the metal parts in the vessel) in the following way:

    1. Connect the M6 bolt underneath the enclosure to the vessel ground. See the below drawing for the location of the chassis earth bolt.

Isolation_transformer_-_Earth_bolt_location.png

Location of the chassis earth bolt.

3.4. AC output neutral to earth link

A GFCI must be installed in the AC output of the isolation transformer. For the GFCI to operate correctly, the AC output neutral must be connected to the AC output earth and ground (= all the metal parts in the vessel).

To link the AC output neutral (N) to earth (PE), place a green/yellow jumper wire (included) between male spade connectors J5 and J7.

Isolation_transformer_-_AC_output_N-PE_link_7000.png

AC output neutral (N) to earth (PE) link.

3.5. Cable cross-section requirements

Use the following minimal cable cross-sections:

Isolation transformer power rating

Voltage

Metric

AWG

7000W

230V

6mm²

AWG 10

3.6. Wiring example

AC_Instalations_-_Boat_-Isolation_transformer.png

Wiring example isolation transformer installed on a vessel connected to shore power.

ID

Description

A

Shore power.

B

Circuit breaker.

C

GFCI (Ground Fault Circuit Interrupter).

D

Shore cable.

E

Isolation transformer.

F

AC loads.

3.7. Linking input and output earth when the vessel is out of the water.

For safety reasons, when the vessel is out of the water (on land) during winter or for maintenance, the vessel earth (PE) conductor must be connected directly to the shore power earth (PE) conductor.

This can be achieved inside the isolation transformer by connecting the yellow/green jumper wire (included) between the male spade connectors J12 and J9, as indicated below.

Isolation_transformer_-_AC_PE_output-input_link_7000.png

AC input earth is connected to AC output earth when the vessel is out of the water (on land) during winter or for maintenance.