Technical Description
MOBILE WORKSTATION WM-NP2
65
Chapter 9 Technical Description
The block diagram shown in Figure 9.1 shows the different sub-units within the Separation
Transformer.
The mains cable connects to the transformer through a high current IEC-320 style connector,
allowing it to be easily replaced if it becomes damaged during use. It is secured to the transformer
by a pair of clamps, to prevent accidental disconnection during use. The protective earth terminal
connects to the metal enclosure of the unit and the output socket earthing system; the line and
neutral conductors connect to the primary side of the transformer via two magnetically operated
circuit breakers sharing a common actuator and an inrush limiting circuit.
As with any transformer, the primary circuit will draw an inrush current surge when it is connected to
the mains supply, which can sometimes be very large, depending on the magnetic state of its core
at the instant it is powered. The inrush limiting circuit inserts a high power thermistor in series with
the primary winding to limit the initial surge, dissipating it as heat. After approximately 0.3 seconds a
relay closes (producing an audible ‘click’) to by-pass the thermistor, both to avoid any steady-state
losses that would adversely affect the load regulation and to allow it to cool in readiness for the next
switch-on.
A green LED on the transformer indicates that it is connected to the mains power supply.
The transformer is wound with a nominal input-to-output ratio of 1:1, with concentric primary and
secondary windings. An additional low voltage secondary winding powers the circuit for the remote
switch. Electrical separation between windings is maintained by overlapping layers of “Melinex”
tape.
The main secondary winding supplies power to the separated output sockets. An additional socket
connects to the remote switch located on the front of the workstation’s top tray, operating a relay to
control the power to the output sockets. This provides a convenient method of turning the entire
system (apart from the transformer itself) on or off from a central point on the mobile workstation.
To isolate the unit from the mains supply, set the remote switch to its stand-by’ position, then
disconnect the mains connector from the wall outlet socket.
A potential equalisation terminal is provided adjacent to the input cable for use where local
regulations require the enclosures of each part of the system be connected to a common earth
point, independently of the mains supply cables. Additional terminals, for connection to the other
components of the system, can be installed by attaching a six-way equipotential terminal strip,
available as an accessory, to each side of the transformer.
A Maintenance and Repair Manual is available from Olympus containing circuit diagrams, parts
lists, descriptions, replacement procedures and other information to assist qualified service
personnel in repairing this equipment.
