Patent Application
20080031752
The pump operation is established with one pump as a backup pump and a pair of lead acid batteries as a backup power supply. The pump control unit serves as replacement for the utility power, in the case of AC power loss and is active for battery power as well. The control unit serves also as an alternative energy device that replaces gas-fueled generators. It is equipped with advanced pump switching logic to accommodate for normal and abnormal pump operation. The pump switching and pump control logic is active for battery power as well as AC power mode.
The pump control unit operates in 3 modes; the user has the option to choose between the 3 modes:
Each pump has a pressure switch that activates either the corresponding or alternate pump, depending on selected application. An additional security switch is also mounted at the maximum allowable water level. In no instance will both pumps cycle simultaneously.
Once the pump control and pumps are configured by a professional, it does not require human interaction since the processes are conducted automatically. The batteries recharge automatically and are maintained at the maximum capacity level. Pumps will be automatically monitored for electrical and mechanical malfunction.
The user task consists of monitoring the unit for abnormal operation as indicated by audio and visual alarms.
The control operates in one of 3 ways depending on the pump configuration:
When the pump pressure switch closes, the pump starts cycling. When the pump pressure switch opens the pump turns off. Under normal condition this cycle continues as described above. If the pump is cycling and the water reaches the maximum level switch, the operation continues followed by a visual and audio alarm.
A special case, defined as the state of overload, is induced when the pump is clogged due to the presence of a substance that cannot be evacuated. The pump draws more power and it can be damaged if it continues to run. Overload condition may also be induced by a short in the pump itself or shorted pump cable. When the pump overload is sensed, the pump shuts down followed by the visual and audio alarm. This condition is maintained until the “overload reset” button is pressed (this should be done by a professional since the pump exerted abnormal operation).
In parallel configuration pump 1 and pump 2, as well as their pressure switches, should be installed at the same level in the sump hole.
Normal operation commences as follows:
If the circuit is in the initial state, the pump control unit waits for the primary pressure switch to close. The unit will automatically determine (due to the minute differences in pressure switch level) which pressure switch will be the primary and which will be the secondary. Both pressure switches should be installed on approximately the same level plane. When the primary pressure switch closes, pump 1 starts cycling first (pump 2 remains inactive at this stage). After the primary pressure switch opens, pump 1 turns off and switches to pump 2 (pump 1 remains inactive at this stage and pump 2 is in the cycle ready state). When the primary pressure switch closes again, pump 2 begins cycling. When primary pressure switch opens again, pump 2 turns off and switches back to pump 1 (cycle ready state). Concerning primary and secondary pressure switch, each switch acts as a backup for the other one. Both pressure switches are connected in parallel and will turn on either of the pumps when one of them is closed and turn off that pump only when both of them are open. Under normal conditions, this cycle continues as described above and ensures equal number of cycles for each pump.
If either of the pumps is cycling and the water reaches the maximum level switch, the operation will be turned over to the pump which was not cycling at that time followed by permanent visual and resettable audio alarm. This condition remains until the “main reset” button, accessible only to plumbers, is pressed.
This operation prevents over flooding due to pump malfunction.
If the primary pump was cycling and the maximum level switch is reached, the pump control unit permanently assigns the operation to the secondary pump which will evacuate the water to the primary pressure switch level. Visual and audio alarms will be activated. If during next secondary pump cycle the maximum level pressure switch is closed again, the secondary pump will continue to run followed by visual and audio alarm.
If the secondary pump was cycling and the maximum level switch is reached, the pump control unit permanently assigns the operation to the primary pump which will evacuate the water to the primary pressure switch level. Visual and audio alarms will be activated. If during next primary pump cycle, the maximum level pressure switch is closed again, the primary pump will continue to run followed by visual and audio alarm.
In the case of overload, the operation is permanently assigned to the pump, which was NOT cycling at that time, followed by permanent visual and resettable audio alarm. This condition leaves the defective pump inactive and the maximum level switch loses its functionality except alarm and visual indication. This condition remains until the “main reset” button is pressed (accessible only to plumbers).
If the overload condition arises on the alternate pump also, both pumps become inactive and remain inactive until the “main reset” button is pressed which will force the unit to its initial state.
In order for either pump to run one switch has to be closed, and for either pump to turn off, both switches have to be open. If only primary pressure switch is bad, secondary pressure switch will take over the function. If only secondary pressure switch is bad, primary pressure switch will take over its function. If both pump pressure switches are bad, no pump cycling will occur even when maximum level pressure switch closes. Both check primary and check secondary pump flashing lights will be on, followed by the audio alarm. If only maximum level pressure switch is bad, no pump circuit switching will occur, the corresponding pump will continue cycling, and the visual and audio alarms will NOT be activated.
In the staggered pump configuration primary pump and the corresponding pressure switch is the circuit which is installed at the ground level in the sump hole. The secondary pump and corresponding pressure switch is the circuit which is installed above the primary circuit.
When the pressure switch of the primary pump circuit is closed, primary pump starts cycling. After its switch opens the primary pump turns off. This operation will repeat four times and after the 4th cycle, the primary pump will be temporarily disabled and it will allow the water to reach the secondary pump which will cycle only once as long as its pressure switch is closed. After the water is evacuated below the level of the secondary pump circuit pressure switch, the pump control unit returns the operation to the primary pump circuit which will continue to remove the remaining water in the sump hole as long as its pressure switch is closed. When the primary pump circuit pressure switch opens, the unit returns to the initial state and the cycle repeats. Under normal conditions this operation ensures the secondary pump check valve clearance and 20% of total cycle counts.
If the primary pump is cycling and the water level reaches the secondary pump pressure switch, the pump control unit will automatically switch to secondary pump circuit, permanently disable primary pump circuit, and indicate permanent visual and resettable audio alarm. When the secondary pump pressure switch opens the secondary pump turns off and waits for next cycle. This operation prevents over flooding due to primary pump circuit malfunction. If during next secondary pump circuit cycle the maximum level pressure switch is closed, the pump will continue to run followed by visual and audio alarm.
If the primary pump was cycling and the maximum level switch is reached, the primary pump will continue to run followed by permanent visual and resettable audio alarm (check pump 1 and pump 2 lights will be on). The secondary pump circuit is disabled due to bad pressure switch.
If the secondary pump was cycling and the maximum level switch is reached, the unit permanently assigns the operation to the primary pump circuit which will evacuate the water to its pressure switch level (ground level) followed by permanent visual and resettable audio alarm. If during next cycle the maximum level pressure switch is closed again, the primary pump will continue to run followed by permanent visual and resettable audio alarm. The warning lights will be lit until “main reset” button is pressed.
In the overload case, the operation is assigned to the pump which was NOT cycling at that time and remains assigned to that pump. This condition leaves defective pump circuit inactive and the maximum level switch loses its functionality except visual and audio alarm. This condition remains until the “main reset” button is pressed.
If the overload condition arises on the alternate pump also, both pumps become inactive and remain inactive until the “main reset” button is pressed which will force the unit to its initial state.
When the water reaches either the secondary pump pressure switch (unless in 20% usage mode), or maximum level switch, or when the unit exerts the overload, there will be an audio alarm followed by visual warning indicating which pump is malfunctioning.
The following invention includes but it is not limited to following features:
Highly efficient DC to AC conversion, transformer less inverter, pump motor soft start, battery bulk charger with trickle charger, 115Vrms/60 Hz sine wave power signal for quieter and cooler pump operation, pump overload protection, backup pump provided with nominal power, 2 cascaded 12V batteries to increase efficiency and prolong the running time, inverter short circuit protection, multiple LED to display the battery and pump status, piezo sound alert, digital volt meter to display present battery voltage, 3 float switches with the third float switch for pump and float switch failure security, 3 operating modes such as single pump, double pump in parallel and double pump in staggered configuration.
Main low voltage power supply for switching logic and driving and sensing circuits is delivered from Transformer T1 at 11 which steps down 120Vac to 14Vac. This voltage is further rectified through Diodes D4 and D5 at 12, and filtered by capacitor C6 at 13. This power is delivered to 12V regulator 28 at 13. From the other side unregulated 24 volts battery voltage at 14 is delivered to 29 voltage regulator through diode D3 at 15. The 29 regulator is controlled by transistor Q1 at 16 which turns the regulator ON and OFF, depending on the status of AC power supply at 17. If AC power is interrupted the transistor is turned OFF through R4 at 18 and the 29 regulator is providing the voltage at the output 19 to supply the 12V regulator through diode D1 at 13.
This method allows generation of an uninterrupted +12V supply at 25 which is distributed through analog and digital active and passive low power components. Also the AC power detector logic and relay driver circuit is using voltage at 17 to obtain the signal at 26 to drive relay RL3 which routes AC or inverted DC battery power to pump relays. Battery voltage is constantly monitored at 20 and 21 and visually displayed on the front panel by a digital volt meter at 14. Low battery voltages will be indicated by visual and audio alarm.
The Sinusoidal Pulse Width Modulation or abbreviated SPWM is generated by SPWM circuitry at 27 which is triggered by crystal oscillator at 22.
Obtained SPWM signals are split into two halves marked as SPWM A at 23 and SPWM B at 24 to provide a signal to high side and low side power switch drivers. Through high speed, high power switching devices the inverter will generate high frequency power signal with a stabile 60 Hz fundamental sinusoidal frequency.
First stage in
Battery charger 56 is a 24V Sealed Lead-Acid Battery Charger. It is configured as dual step constant current charger to provide a constant current of approximately 4 amperes at variable battery voltage. The battery charger is short circuit protected. Once the battery voltage reaches certain voltage level, the charger switches to trickle charge current to maximize and maintain highest possible battery capacity. The power supply for the battery charger 57 is a 150W switch mode power supply which is powered by utility 120Vac 59. It is adjusted to provide a constant voltage level of 30 volts.
Diode D2 at 58 is connected in parallel with the battery to prevent the damage to pump control system in the case of reversing the battery polarity.
In DC to AC inverter stage once the +Bus 53 and −Bus 54 voltage has been established, the +Bus and −Bus high DC voltage is further modified by multiplicity of paralleled power switching devices at 70 and 71, which are connected in half bridge configuration. The power switches at 77 and 78 are driven by isolated high side driver at 79 and low side drivers at 80. These drivers are controlled by SPWM A 81 and SPWM B 82 signals. Through this DC modification we obtain a high frequency SPWM power signal at 83 with 60 Hz sine wave fundamental frequency. This signal is filtered through inductor 72 and capacitor 73 configured as low pass filter to obtain 115V˜60 Hz voltage at 74 to drive sump pumps.
The half bridge configuration has the advantage over full bridge configuration since it utilizes half as many power switching devices as needed in full bridge configuration. Also by paralleling power switching devices the effective ON resistance reduces and minimizes the overall conduction losses. High speed power switching devices are employed to reduce switching losses. Diodes 75 and 76 are connected in parallel to switching devices to protect them from back EMF from highly inductive load.
Inverted DC battery power from the inverter circuit at 74
Pump 1 at 40 is turned ON and OFF by RL1 at 36 which supplies power to pump 1 through 38. Pump 2 at 41 is turned ON and OFF by RL2 at 37 which supplies power to pump 2 through 39. These relays are controlled by advanced switching logic.
The advantage of this type of pump switching control over existing pump controls is the presence of 2 AC pumps supplied with the nominal voltage and the 50% utilization on each pump. We employ 3 float switches which alternate pump operation according to their status. This minimizes the possibility of system failure due to stuck float switches, clogged pump, blocked pump or idling of the pump over long periods of time. Note that this same flowchart logic is applicable when the AC power failure occurs and the system is running on DC backup power supply.
This flowchart starts at 100. At 101 both pumps are idling and awaiting the float switch 1 or float switch 2 closure at 102. Notice that in parallel configuration both float switches from pump 1 and pump 2 are connected in parallel and will turn ON either pump if any of these float switches are closed and turn OFF that pump only if both of them are open. From the standpoint of implementation of this switching logic circuitry this is necessary but also desirable feature to minimize the risk of pump failure due to bad or stuck float switches. As soon as one of the float switches is closed at 102, pump 1 will cycle first at 103. A visual indication informs the user of pump operation at 104. During pump cycling the pump condition is monitored to sense if the pump is operating normally. Overload at 105 will be triggered if the pump is either stuck or drawing excessive current.
A third float switch is implemented and monitored to indicate the maximum liquid level in the sump hole. If the sump pump is not pumping sufficient amount of liquid due to blockage of liquid, the maximum level float switch at 106 is triggered and forces the system to alternate pumps. In normal case the primary or pump 1 will evacuate liquid below both pump 1 and pump 2 float switches at 107 and turn off the pump 1 at 108. At 109 the float switches SW1 and SW2 are expecting next liquid inrush and both pumps will idle until one of the float switches closes and turn ON the alternative pump at 110. Note that in this scenario each pump will act as backup pump for the other because they are assigned to perform exactly same tasks.
When pump 2 is cycling the system will provide visual indication at 111 to inform the user of pump operation. The pump will be monitored for overload condition at 112 and maximum liquid level by float switch SW3 at 113. If system continues to function normally both pump float switches will open at 114 and bring the system back to initial start position at 101.
Sump pumps are prone to failure because of continuous exposure to humidity, deterioration from corrosion, and they are subject to foreign object liquid blockage. Additionally, larger objects such as stones could cause the impeller blockage and cause pump overload.
If pump 1 was cycling and failed due to overload at 105 or maximum liquid level at 106, the flowchart continues at 118 displaying the pump 1 overload condition or check pump 1 indication due to maximum liquid level at 117. The system also turns ON the sound alarm to alert the user of abnormal pump operation.
At 119 pump 1 will be turned OFF and since the float switches are already activated at 120, pump 2 will take over the cycling operation immediately and evacuate remaining liquid from the sump hole at 121. The user is visually informed of pump activity at 122. The system checks for overload condition at 123 or maximum liquid level at 124-125. As long as neither of the float switches is activated at 127 the system keeps cycling pump 2 at 121. Only when both float switches are deactivated the system will turn OFF pump 2 and bring pump 2 back into a stand-by position at 119.
Note that due to overload condition at 105 or maximum allowable liquid level condition at 106, pump 1 is permanently disabled and will not be employed in further system operation. Pump 2 remains the only working pump and the user is alerted and given the opportunity to take action to bring pump 1 back to normal operation. Furthermore if pump 2 is allowed to cycle and due to failure causes an overload at 123, the system will come to a stop, indicate visually and audibly the failure condition at 128, and idle in OFF mode at 115 until main reset switch is depressed at 116. The main reset switch will reset all warning indicators and should be used only if the pump problems are resolved. However if pump 2 allows the liquid to rise to maximum allowable level at 124, the system will NOT interrupt pump 2 operation, even if failure due to pump blockage is suspected, but rather allow it to further pump the liquid since pump 2 is the only working pump. User will be alerted with audio and visual indicators at 126.
As in previous case of pump 1 failure due to overload or due to maximum liquid level this part of the chart will follow the same exact logic for pump 2 as for pump 1.
If pump 2 was cycling and failed due to overload at 112 or maximum liquid level at 113, the flowchart continues at 129 displaying the pump 2 overload condition or check pump 2 indication due to maximum liquid level at 130. The system also turns ON the sound and visual alarm to alert the user of abnormal pump operation.
At 131 pump 2 will be turned OFF and since the float switches are already activated at 132, pump 1 will take over the cycling operation immediately and evacuate remaining liquid from the sump hole at 133. The user is visually informed of pump 1 activity at 134. The system checks for overload condition at 135 or maximum liquid level at 136-137. As long as neither of the float switches are activated at 139, the system keeps cycling pump 1 at 133. Only when both float switches are de-activated system will turn OFF pump 1 and bring pump 1 back into a stand-by position at 131.
Note that due to overload condition at 112 or maximum allowable liquid level condition at 113, pump 2 is permanently disabled and will not be employed in further system operation. Pump 1 remains the only working pump and the user is alerted and given the opportunity to take action to bring pump 2 back to normal operation. Furthermore if pump 1 is allowed to cycle and due to failure cause an overload at 135, the system will come to a stop, indicate visually and audibly the failure condition at 140, and idle in OFF mode at 115 until main reset switch is depressed at 116. The main reset switch will reset all warning indicators and should be used only if the pump problems are resolved. However if pump 1 allows the liquid to rise to maximum allowable level at 136, the system will NOT interrupt pump 1 operation even if failure due to pump blockage is suspected, but rather allow it to further pump the liquid since pump 1 is the only working pump. User will be alerted with audio and visual indicators at 138.
Many sump wells are not wide enough to fit two pumps next to each other. In this situation staggered pump configuration is preferred. In staggered configuration primary pump has a duty cycle of 80% and secondary or backup pump a duty cycle of 20%. This way backup pump will be less exposed to possible failure.
Staggered configuration employs 3 float switches which alternate pump operation according to pump status. Backup or secondary pump float switch acts as backup float switch for pump 1. Float switch 3, which indicates maximum allowable liquid level, act as backup float switch for pump 2 and also for pump 1. This way primary pump 1 is well protected against float switch failure.
This switching logic minimizes the possibility of system failure due to stuck float switches, clogged pump, blocked pump, or idling of the pump over a long period of time.
It is important to note that in the case of AC power failure the pump 1 cycle counter will be disabled to eliminate liquid elevation due to pump checking procedure.
The flowcharts in
This flowchart starts at 200. At 201 a counter that counts pump 1 cycle is initiated. Both pumps are idling at 202 and awaiting pump 1 float switch closure at 203. When pump 1 float switch is activated, pump 1 turns ON at 204. A visual indication informs the user of pump 1 operation at 205. At 206 pump 1 is continuously monitored for overload condition, and at 207 for maximum liquid level. Once the liquid is evacuated from the sump pump well pump 1 float switch opens and turns OFF pump 1. This cycle repeats four times unless there is an AC power failure in which case the pump 1 cycle counter is disabled and the operation continues through 209 where status of switch 1 is monitored.
If however the AC power is not interrupted and the counter continues to count pump 1 cycles, when called upon duty 5th time, the pump 1 is not allowed to cycle even if pump 1 float switch is activated at 213. The liquid will be allowed to elevate to pump 2 float switch at 214 and turn ON pump 2 for testing purposes at 215. A visual indication informs the user of pump 2 operation at 216. Pump 2 is continuously monitored for overload condition at 217 and maximum allowable liquid level at 218. If there is no failure the process continues monitoring the condition of pump 2 float switch at 219. As long as this float switch is activated the pump 2 will continue to cycle. Once pump 2 float switch opens at 219, liquid level is at pump 2 float switch level. In order to evacuate the remaining liquid, the operation is turned over to pump 1 again at 220 and allows the liquid to be evacuated from the sump hole. The user is visually informed of pump activity at 221. During pump 1 cycling, overload condition at 222 and maximum liquid level at 223 is continuously monitored. Note that for pump 1 the maximum liquid level will be the level of pump 2 float switch. Pump 1 will cycle as long as pump 1 float switch is activated at 224. A visual indication informs the user of pump 1 operation at 221. When pump 1 float switch deactivates at 224 the whole cycle starts again from beginning at 200.
If pump 1 was cycling and failed due to overload at 206 or maximum liquid level at 207 the flowchart continues at 226 displaying the pump 1 overload condition or check pump 1 indication due to maximum liquid level at 225. The system also turns ON the sound and visual alarm to alert the user of abnormal pump operation.
At 227 pump 1 will be turned OFF. At this point the system waits for liquid level to rise to pump 2 float switch level at 228 to turn ON pump 2 at 229.
The user is visually informed of pump activity at 230. The system checks for overload condition at 233 or maximum liquid level at 231. As long as pump 2 float switch is activated the system keeps cycling pump 2 at 227. As soon as pump 2 float switch is deactivated, the system turns OFF pump 2 and brings pump 2 back in stand by position at 227. At this point liquid level remains at pump 2 float switch level.
Note that due to overload condition at 206 or maximum allowable liquid level condition at 207, pump 1 is permanently disabled and will not be employed in further system operation. Pump 2 remains the only working pump and the user is given the opportunity to take action and bring pump 1 to normal operation. Furthermore if pump 2 is allowed to cycle and due to failure causes an overload at 233, the system will come to a stop, indicate visually and audibly the failure condition of pump 2 at 259, and idle in OFF mode at 258 until main reset switch is depressed at 260. The main reset switch will reset all warning indicators and should be only used if pump problems are resolved.
However if the pump 2 cycles and allows the liquid to rise to maximum allowable level at 231, the system will NOT interrupt pump 2 operation even if failure due to pump blockage is suspected, but rather allow it to further pump the liquid since pump 2 is the only working pump. User will be alerted with audio and visual indicators at 232.
Note that same flowchart will also hold for overload condition of pump 1 at 222 and maximum allowable liquid level condition at 223.
Pump 2 cycles only periodically for testing purposes. If during cycling pump 2 exhibits overload condition at 217, the operation continues at 235 alarming the user visually and audibly of abnormal pump operation.
At 237 pump 2 will be turned OFF. Since both float switches are already activated, pump 1 will take over the cycling operation immediately and evacuate remaining liquid from the sump hole at 237. The user is visually informed of pump activity at 238. The system checks for overload condition at 239. When pump 2 fails both pump 1 and pump 2 float switches are activated and the cycling of pump 1 will continue until liquid is evacuated from sump hole and pump 1 float switch is deactivated at 243. At this point pump 2 float switch acts as sensor for maximum liquid level of pump 1 at 241. The system monitors the status of pump 1 float switch at 245, idles at 244, and turns pump 1 ON at 237 if pump 1 float switch is activated at 245.
Note that due to overload condition at 217, pump 2 is permanently disabled and will not be employed in further system operation. Pump 1 remains the only working pump and the user is given the opportunity to take action and bring pump 2 to normal operation. Furthermore if pump 1 is allowed to cycle and due to failure causes an overload at 239, the system will come to a stop, indicate visually and audibly the failure condition at 257, and idle in OFF mode at 258 until main reset switch is depressed at 260. The main reset switch will reset all warning indicators and should only be used if the pump problems are resolved.
However if the pump 1 allows the liquid to rise to maximum allowable level at 241, the system will NOT interrupt pump 1 operation even if failure due to pump blockage is suspected, but rather allow it to further pump the liquid since pump 1 is the only working pump. User will be alerted with audio and visual indicators at 242.
Pump 2 cycles only periodically for testing purposes. If during this cycling pump 2 exhibits maximum liquid level condition at 218, the flowchart continues at 236 alarming the user visually and audibly of abnormal pump operation.
At 246 pump 2 will be turned OFF and since the both float switches are already activated, pump 1 will take over the cycling operation immediately and evacuate remaining liquid from the sump hole at 246. The user is visually informed of pump activity at 247. The system checks for overload condition at 248. The cycling of pump 1 will continue until liquid is evacuated from the pump hole and pump 1 float switch deactivates at 254. At this point pump 2 float switch at 253 as well as maximum liquid level float switch 3 at 250 act as sensor for maximum liquid level of pump 1. The system monitors the status of pump 1 float switch at 256, idles at 255, and turns pump 1 ON at 246 if pump 1 float switch is activated at 256.
Note that due to maximum liquid level condition at 217, pump 2 is permanently disabled and will not be employed in further system operation. Pump 1 remains the only working pump and the user is given the opportunity to take action and bring pump 2 in normal operation. Furthermore if pump 1 is allowed to cycle and due to failure causes an overload at 248, the system will come to a stop, indicate visually and audibly the failure condition at 257, and idle in OFF mode at 258 until main reset switch is depressed at 260. The main reset switch should be only used if the pump problems are resolved. However, if the pump 1 allows the liquid to rise to pump 2 float switch that represents maximum allowable level for pump 1 at 253, the system will NOT interrupt pump 1 operation even if failure due to pump blockage is suspected, but rather allow pump 1 to further pump the liquid since pump 1 is the only working pump. User will be alerted with audio and visual indicators at 251.
In both instances of parallel and staggered switching logic, there are many variation of switching sequences of all three float switches in failure conditions. These failure variations are not included in the flowchart, however the system provides maximum security against pump and float switch failure in any switching scenario.
The flowchart in
The optimal use of this system is not to be used with single pump, but it is able to run in single pump mode if one of the paralleled or staggered pumps failed and is missing. This mode is implemented as a sub circuit of a staggered circuit.
The flowchart starts at 300 with idling pump at 301. Pump 1 float switch is monitored and when activated, pump 1 turns ON at 303. A visual indication informs the user of pump 1 operation at 304. Pump 1 continues cycling until the float switch opens at 309.
Pump 1 is monitored for overload and maximum liquid level condition. If pump allows the liquid to rise to maximum allowable level at 306, the system will NOT interrupt pump operation, even if failure due to pump blockage is suspected, but rather allow it to further pump the liquid since this is the only pump. User will be alerted with audio and visual indicators at 307.
Furthermore if pump 1 is cycling and due to failure causes an overload at 305, the system will come to a stop, indicate visually and audibly the failure condition at 308, and idle in OFF mode at 310 until main reset switch is depressed at 311. The main reset switch will reset all warning indicators and should be only used if the pump problems are resolved.
This application claims the benefit of PPA Ser. No. 60/779,333, filed Mar. 3, 2006 by the present inventor(s).
| Number | Date | Country | |
|---|---|---|---|
| 60779333 | Mar 2006 | US |
