Warnings, Cautions and Notes    Edition 04/04 
  MICROMASTER 420 
2  Compact Operating Manual 
Warnings, Cautions and Notes 
The following Warnings, Cautions and Notes are provided for your safety and as a 
means of preventing damage to the product or components in the machines 
connected.  
Specific Warnings, Cautions and Notes that apply to particular activities are 
listed at the beginning of the relevant chapters and are repeated or supplemented 
at critical points throughout these chapters. 
Please read the information carefully, since it is provided for your personal safety 
and will also help prolong the service life of your MICROMASTER 420 Inverter and 
the equipment you connect to it. 
WARNING 
 This equipment contains dangerous voltages and controls potentially 
dangerous rotating mechanical parts. Non-compliance with Warnings or failure 
to follow the instructions contained in this manual can result in loss of life, 
severe personal injury or serious damage to property. 
 Only suitable qualified personnel should work on this equipment, and only after 
becoming familiar with all safety notices, installation, operation and 
maintenance procedures contained in this manual. The successful and safe 
operation of this equipment is dependent upon its proper handling, installation, 
operation and maintenance. 
 The DC link of all MICROMASTER modules remains at a hazardous voltage 
level for 5 minutes after all voltages have been disconnected. Therefore always 
wait for 5 minutes after disconnecting the inverter from the power supply before 
carrying out work on any modules. The drive unit discharges itself during this 
time. 
 This equipment is capable of providing internal motor overload protection in 
accordance with UL508C section 42. Refer to P0610 (level 3) and P0335. 
Motor overload protection can also be provided using an external PTC via a 
digital input. 
 This equipment is suitable for use in a circuit capable of delivering not more 
than 10,000 symmetrical amperes (rms), for a maximum voltage of 230/460 V 
when protected by an H or K type fuse, a circuit breaker or self-protected 
combination motor controller. 
 Use Class 1 60/75 °C copper wire only with the cross-sections as specified in 
the Operating Instructions.. 
 The mains input, DC and motor terminals carry dangerous voltages even if the 
inverter is inoperative, wait 5 minutes to allow the unit to discharge after 
switching off before carrying out any installation work. 
NOTES 
 Before installing and commissioning, please read these safety instructions and 
warnings carefully and all the warning labels attached to the equipment.  
 Make sure that the warning labels are kept in a legible condition and replace 
missing or damaged labels. 
 Maximum permissible surrounding ambient temperature is 50°C. 
 
!