Abstract: A system for controlling operation of a progressing cavity pump to maintain the motor operating under power disturbance conditions. For a blackout condition, a backspin controller uses regenerative power to provide controlled deceleration of the pump, counteracting backspin and preventing backspinning freely. For a brownout condition, a power dip controller weakens the motor field to maximize pump production consistent with reduced input power availability. For a phase loss or voltage imbalance condition, a phase loss controller reduces motor power output to keep drive system output power at or below single phase capacity.

Abstract: A system for controlling operation of a progressing cavity pump to maintain the motor operating under power disturbance conditions. For a blackout condition, a backspin controller uses regenerative power to provide controlled deceleration of the pump, counteracting backspin and preventing backspinning freely. For a brownout condition, a power dip controller weakens the motor field to maximize pump production consistent with reduced input power availability. For a phase loss or voltage imbalance condition, a phase loss controller reduces motor power output to keep drive system output power at or below single phase capacity.

Abstract: A system for controlling operation of a progressing cavity pump to maintain the motor operating under power disturbance conditions. For a blackout condition, a backspin controller uses regenerative power to provide controlled deceleration of the pump, counteracting backspin and preventing backspinning freely. For a brownout condition, a power dip controller weakens the motor field to maximize pump production consistent with reduced input power availability. For a phase loss or voltage imbalance condition, a phase loss controller reduces motor power output to keep drive system output power at or below single phase capacity.

Abstract: An oesophagus seal for sealing the oesophagus in a slaughtered animal comprises a plug (10) for insertion into the oesophagus (40) and a retainer in the form of a clamp (20) which internally engages and clamps to tissues of the oesophagus (40) to resist disengagement of the plug. The plug (10) has an outer peripheral clamp surface (13) and the clamp (20) is in the form of a clamp ring (21) which clamps the internal mucosa (41) of the oesophagus (40) between the clamp ring (21) and the outside clamp surface (13). The plug (10) has a reduced diameter neck (15) and a conical ramped outer surface (16) leading to the clamp surface. The clamp ring (21) is initially located beyond the neck (15) and is advanceable so that tissues (41) surrounding and projecting into the neck portion (15), e.g.

Abstract: Cyclic hemiacetals thereof of the formula ##STR1## where A is saturated hydrocarbyl of 2 to 16 carbon atoms which may contain --O-- as a bridge member are prepared by subjecting cyclic ethers of the formula ##STR2## where A has the abovementioned meaning, to anodic oxidation in aqueous solution at current densities of over 30 mAcm.sup.-2.