Instructions / Assembly
Operation PS 2 500 / PS 2 750 / PSA 2 500
24  wc_tx001986gb.fm
4.3 Motor Protection System (Motor Protector)
Circle Thermal protector (PS 2 750)
Miniature Protector (PS 2 500, PSA 2 500)
The pump has a built-in motor protection system. If an excessive 
current is detected (PS 2 750) or the motor overheats, for reasons 
such as the following, the pump will automatically stop operating 
regardless of the water level, to protect the motor:
• Change in supply voltage polarity
• Overload
• Open-phase operation or operation under constraint
Note: Always determine the cause of the problem and resolve it before 
resuming operation. Simply repeating cycles of stopping and restarting will 
end up damaging the pump. Do not continue operation at very low lift, low 
water level, or while the strainer stand is clogged with debris. Not only will 
performance suffer, but also such conditions may cause noise, heavy vibra-
tion, and malfunctioning.
4.4 Operating Cycle of Automatic Type 
Stage Level Relay Unit Pump Water Level
1 When electrodes (b) of level relay units (a) 
submerge under water, the resulting elec-
tric current causes the pump to operate. 
(Electrodes sensing the electricity)
Operation 
starts 
(drainage)
Falls
2 When the water level goes below the 
height of the electrodes, a timer is acti-
vated. The pump keeps operating. (No 
electric current –>Timer activates.)
Operation 
remains 
(drainage)
Falls
3 The pump keeps operating for approxi-
mately one minute. (The pump resumes 
the operation if the electrodes contact the 
water again within one minute.)
Operation 
remains 
(drainage)
Falls
4 The pump stops one minute later. (The 
pump may not stop operating for a longer 
period of time.)
Operation 
stops
Rises
5 When the water level rises again and the 
electrodes touch the water, the pump 
starts operating again. (Electrodes sens-
ing the electricity)
Operation 
starts again 
(drainage)
Falls










