Operations Manual
Delta Min Collar RPM – The value transmitted will be the difference between the collar RPM and min collar RPM, In order to calculate the min collar RPM the following calculation needs to be carried out manually at surface. Min Collar RPM = Collar RPM – Delta Min Collar RPM Delta Max Collar RPM – The value transmitted will be the difference between the collar RPM and max collar RPM, In order to calculate the max collar RPM the following calculation needs to be carried out manually at surface. Max Collar RPM = Collar RPM + Delta Max Collar RPM If a large difference between Min Collar RPM and Max Collar RPM is observed, this can be an indication of stick-slip occurring. Toolface Position Error – This is calculated as the difference between the desired toolface and the actual toolface whilst steering, the range transmitted is between -24 – +24 deg. This can be used as an indication of tool performance, high toolface errors indicate a reduction in steering performance, causes include but are not limited to shock, vibration, high stick-slip, low generator voltage, or a possible internal tool fault. Mean Motor Current – The mean motor current indicates how much power is required by the motor to accurately place the valve which diverts flow enabling the RST to steer accordingly. Under acceptable conditions the value should be below 2 amps, any values above this may be an indication that the RST is not performing as required. If the motor current reaches above 3 amps this indicates that the valve may have locked up and the RST will be unable to steer. Max Motor Current – The minimum transmitted value is 3 amps, if values are observed of above 3 as stated above the valve has locked up or is intermittently sticking. –
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