Bronson MII-D Series User manual
Instruction Manual
Bronson MII-D Series
Toroidal Core Isolation Transformer
Models: MII-D 1000 MII-D 4500
English
Toroidal Core Isolation Transformer
Bronson MII-D Series
Toroidal Core Isolation Transformer
Instruction Manual
Before operating this product, please read these instructions carefully
Thank you for selecting this Bronson MII-D Toroidal Core Isolation Transformer.
This transformer allows the creation of an AC circuit (secondary circuit of the
transformer) isolated from the AC power supply (primary circuit of the transformer).
This isolation transformer furthermore allows the conversion of 220 Volts AC
power supply into 110 Volts AC. This manual is a guide to install and use the
transformer. It includes important safety instructions for the operation and correct
installation of the transformer. If you should have any problems with the
transformer, please refer to this manual before contacting customer service.
Models: MII-D 1000 MII-D4500
1. Introduction to the Isolation Transformer
a. Operating Elements of the Isolation Transformer MII-D 4500
Bronson MII-D Series
Toroidal Core Isolation Transformer
Instruction Manual
Main switch
110V Output Socket
Ground Connection /
Disconnection Switch
Power indicator LED
Bottom View
Front View
3
Top View
Output Circuit Breakers
Input Circuit Breakers
Secondary Circuit
breakers (Output side)
4
Primary Circuit
Breakers (Input Side)
Terminal port 110V & 220V
input with automatic
voltage detection
Terminal port 110V output
PE, against the case of
the isolation transformer
110V USA outlets
Bronson MII-D Series
Toroidal Core Isolation Transformer
Instruction Manual
b. Operating Elements of the Isolation Transformer MII-D 1000
Main switch
110V Output Socket
Ground Connection /
Disconnection Switch
Power indicator LED
Bottom View
Front View
5
Bronson MII-D Series
Toroidal Core Isolation Transformer
Instruction Manual
Top View
Circuit breaker
110V USA outlets
110 and 220V IEC
input (L+N+PE)
with automatic
voltage detection
110V terminal
output (L+N)
6
Bronson MII-D Series
Toroidal Core Isolation Transformer
Instruction Manual
7
c. Notes
1. The USA sockets can be run as grounded to the case or as ungrounded - depending on the usage
requirement - there is a switch allowing the selection of grounded or ungrounded mode. See
discussion on PE grounding in Section 2: Operation
2. The L,N screw terminals outlets are used for a fully isolated connection on the secondary side of
the transformer.
3. For safety reasons please consider to connect your devices to the isolation transformer output via
an RCD (residual current device). RCDs are available as plugs, power strips, as well as DIN rail switches.
4. Make sure the power is disconnected before rewiring.
5. This transformer automatically detects the input voltage. At an input voltage between 200 and 250V,
the input will be detected and output voltage will be stepped down to the secondary side of the
transformer to half of the input voltage (input of 220 will output 110, input of 240 will output 120).
At an input voltage between 100 and 130V, the input will be automatically detected the output
voltage maintained at the same level as the input but isolated on the secondary side of the transformer.
Size name Maximum
capacity Operating
capacity
MII-D 1000 1000 Watts
4500 Watts
800 Watts
3600 Watts
4A at 230V input
8A at 110V input IEC input 110 or
220V (Automatic
voltage detection)
Screw Terminal 110
or 220V (Automatic
voltage detection)
Screw terminal
& USA Socket
110V
Screw terminal
& USA Socket
110V
15A at 230V input,
30A at 110V input
Yes
NoMII-D 4500
Circuit breaker
current protection Soft
starter Input Output
d. Specifications
Bronson MII-D Series
Toroidal Core Isolation Transformer
Instruction Manual
8
Input voltage
Core construction
Efficiency
100-130V or 200-250V
Toroidal core
98%
Phase Single phase
Wave form Sine wave, no distortion
Display
Protection
Ventilation
Green LED
Isolated
Over temperature protection: 130±10°C
Overload and short circuit protection: Circuit breaker switch
Fan for cooling the core when heated by heavy load (MII-D 4500)
Operation Temperature
Storage Temperature
Operation Relative Humidity
e. Wiring Diagram and Grounding of the Transformer
Toroidal Core Isolation Transformer
Switch
Ground Switch
IEC Input Screw Terminal OutputOutput Plug
0°C~40°C
15°C~45°C
10%-20%RH, Non-condensing
Environmental
Corresponds to the input voltage at an input voltage between 100V and
130V Corresponds to half the input voltage at an input voltage between
200V and 250V.
Output voltage
H
F
PE
L N PE
L N
RED
L
BK
N
Bronson MII-D Series
Toroidal Core Isolation Transformer
Instruction Manual
2. Operation of the Isolation Transformer
Before using the isolation transformer make sure that the conguration of all connections correspond
to the selected application, note that for some applications it may be desirable to maintain the PE ground
on the Output Sockets across the primary and secondary sides of the transformer by switching the
ground connection switch to the ON position, in the following cases it will be desirable to switch this
OFF:
If this isolation transformer is used to protect from electric shock when operating or repairing AC
devices, make sure that the connected device will not be connected to the ground of the transformer.
If using the USA output sockets, switch the ground connection switch to OFF position.
a. To protect from electric shock when operating or repairing AC devices
If an isolation transformer is used in the testing of electrical equipment it is always the measured object
but not necessarily the measuring device (such as an oscilloscope) that has to be connected to an isolation
transformer. Make sure that the measured object will not be connected to the ground of the transformer.
If using the USA output sockets, switch the ground connection switch to the OFF position.
b. To protect from electric shock when testing electrical devices with a
measuring device
If this isolation transformer is used to connect a boat or ship to shore power, make sure that the secondary
circuit will not be connected to the ground of the transformer. If using the USA output sockets, switch the
ground connection switch to the OFF position. If the boat has a dedicated AC ground, this can be used and
the neutral and ground wires can be bridged at the secondary side of isolation transformer. Thus,
any leaking current will return to the transformer on the boat or ship, protecting everyone in the water.
It will furthermore prevent galvanic corrosion, which can occur if boats or ships in a marina or in a
harbor are connected through the ground connection of a shared power supply. Galvanic corrosion
affects the metal underwater parts, such as ship propellers or metal ttings, and it is prevented by isolating
the circuit on the boat or ship (secondary circuit) from the shore power (primary circuit). On the secondary
side of the isolation transformer it is recommended to use an RCD (residual current device), which
will interrupt the circuit in case of any current leakage causing unequal amount of current at L and N.
c. To avoid corrosion and protect from electric shock when using AC shore
power on a boat or ship
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Bronson MII-D Series
Toroidal Core Isolation Transformer
Instruction Manual
Procedure:
(1) Before connecting electrical devices to this isolation transformer make sure that the power of the
connected devices will not exceed the capacity of the isolation transformer.
For continuous operation the load from the connected devices should not exceed 80% of the
power of the transformer.
(2) Make sure that input voltage corresponds with allowable input thresholds of the transformer.
(3) Connect the isolation transformer with the power supply. Always make sure that the transformer is
connected to the ground connection of the power supply - use a AC ground testing plug to indicate
if your AC grid power is properly grounded.
(4) Connect your appliance to the isolation transformer. Make sure that all appliances are turned off
when connecting them with the isolation transformer. If the ungrounded output is to be used,
make sure the grounding switch is set to OFF position.
(5) Push the power switch off the isolation transformer to the ‘ON’ position and wait until the green
LED will light up.
(6) Turn on your appliance.
(7) The circuit breakers trip and open the circuit if the transformer is overloaded with too much power
from the connected appliances. If this happens, unplug the transformer from the power supply
and remove all connected appliances. Turn off the power switch off the transformer and press the
circuit breakers. Wait a few minutes. Restart at (1).
3. Caution
- To reduce the risk of electric shock and re, do not remove the cover of this device. There are no
user serviceable parts inside.
- To reduce the risk of ele ctrical shock, do n o t expose the isola t ion transformer t o rain, moisture or liquid s.
This unit is only suitable for indoor applications in dry rooms.
- Operate this isolation transformer only with dry clothes and hands.
- To reduce the risk of electrical shock, check if the power cable is properly inserted.
- Do not cover the ventilation openings and the ventilator of this isolation transformer.
- Do not overload this isolation transformer beyond its capacity.
- Do not change internal wiring of this isolation transformer.
- Avoid strong shaking and tipping over this isolation transformer.
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Bronson MII-D Series
Toroidal Core Isolation Transformer
Instruction Manual
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