| 摘要 |
The invention is a downhole petroleum well tractor having a main body (0) connectable to an electrical conductor logging cable (5) from a surface high voltage DC power supply (50), characterized by said main body (0) comprising a common HV DC power line (4) provided with high-voltage DC power supplied from said electrical cable (5); two or more HV DC branch power lines (40) from said common HV DC power line (4), each said HV DC branch power line (40) feeding power to a HV motor drive electronic unit (21) for a drive motor (2); each said drive motors (2) driving one or more drive devices (6) for running on and along a wall in a well for moving said tractor; separate HV DC circuit breaker units (8) on each said HV DC branch power line (40), each said HVDC circuit breaker (8) unit comprising control means (82, 86, 88) arranged for monitoring a current (I) on said HV DC branch power line (40) and controlling a HV DC power switch (84) on said HV DC branch power line (40) to break said current (I) if said current (I) exceeds said set current level (Imax). Each said HV circuit breaker unit (8) is arranged to disconnect its associated motor (2) in case of said associated motor (2) fails, by detecting an increased current above a set current level, in order to prevent shorting said HV power line (4), thus maintaining operation of the other motors (2) of the tractor. |
