GB2491349A

GB2491349A - Power supply for welfare unit

Info

Publication number: GB2491349A
Application number: GB1108893.7A
Authority: GB
Inventors: Francis Stanley Chapman
Original assignee: Advanta Ltd
Current assignee: Advanta Ltd
Priority date: 2011-05-26
Filing date: 2011-05-26
Publication date: 2012-12-05
Anticipated expiration: 2031-05-26
Also published as: GB2491349B; GB201108893D0

Abstract

An electrical power supply system for a welfare facility has an electrical power feed unit 12 which feeds electrical power to components in the mobile bathroom. The system includes a rechargeable battery 10 and a generator set 13 including an internal combustion engine, arranged to charge the battery 10, the battery and the generator set being arranged to supply electrical power to the feed unit 12. A plurality of sensors are arranged to monitor at least the state of charge of the battery and the power demand of the mobile toilet, and a telemetry control system 16 receives the outputs of the sensors and transmits corresponding data to a remote control location. Operation of the generator set 13 is controlled dependent on instructions received from the remote location on the basis of the transmitted outputs of the sensors. The output of the generator is set primarily to charge the battery but can supplement the battery during peak power usage. Preferably the peak power output of the generator is less than the peak power demand. Fresh 19 and waste water tanks are included and monitored.

Description

POWER SUPPLY FOR WELFARE UNIT

This invention concerns a welfare unit. In particular, this invention relates to a power supply system for a welfare unit as well as a welfare unit incorporating such a power supply system. Further, the invention relates to a method of operating a welfare unit, to minimise the power consumption thereof.

Contractors and builders are required by current health and safety legislation to provide suitable welfare facilities for people working on a construction site. Such facilities will normally include toilet and washing facilities and sometimes rest-room and canteen facilities as well. In the case of work being undertaken on an existing building or in a town, the provision of suitable welfare facilities is not usually a problem and an existing building may have an area set aside for those. Other times, a separate welfare unit must be provided for the people working on the site and if no mains water, drainage nor electricity is immediately available, then the welfare unit must be wholly self-contained.

Some large contractors purchase self-contained welfare units which may be moved from place to place as the need arises, where construction work is undertaken. Otherwise, a self-contained welfare unit may be hired from a rental firm and then the maintenance of the unit is then the responsibility of the rental firm rather than the contractor. A typical period of hire might be twelve weeks and though the rental firm would prefer not to have to attend a rented-out unit during that period, experience shows that at least some maintenance of the unit during that period is usually required.

A self-contained welfare unit will normally include a rechargeable battery such as a lead-acid accumulator, or a bank of such batteries (but referred to hereinafter simply as a battery), to supply electrical power for lighting and operation of at least one water pump for the supply of running water. Heating for the water may also be provided as well as space heating for the unit as a whole and often this is powered by bottled gas stored externally of the unit. The battery must periodically be recharged and this may be done by replacing a discharged battery by a freshly charged one, though it is known to employ solar panels to supply charging current to the battery during periods of sunlight, to prolong the period between battery changes.

In our earlier W099/63225, there is described and claimed a welfare unit including a water pump assembly powered by a battery, wherein the system has been configured to minimise the use of electricity by the water pump. In this way, and by virtue of other measures as well, both the consumption of water and electricity by the welfare unit may be reduced.

This invention has come about consequent upon development of a welfare unit such as is described in W099/63225, in an attempt to minimise the electrical power consumption of a welfare unit and also to prolong the interval between maintenance calls for the servicing of a welfare unit.

In accordance with one aspect of this invention, there is provided an electrical power supply system for a welfare unit, comprising: -an electrical power feed unit arranged to feed electrical power to components in the welfare unit; -a rechargeable battery connected to the power feed unit; -a generator set including an internal combustion engine and arranged to charge the battery and supply electrical power to the feed unit; -a plurality of sensors arranged to monitor at least the state of charge of the battery and the power demand of the welfare unit; and -a telemetry control system receiving the outputs of the sensors and transmitting corresponding data to a remote location, and controlling operation of the generator set dependent on instructions received from said remote location.

It will be appreciated that the power supply system of this invention is expressly intended for use with a self-contained welfare unit having no mains electricity connection and no mains water supply. At least some of the facilities provided within the welfare unit are powered by electricity supplied from the rechargeable battery through the power feed unit and a sufficient level of charge is maintained in the battery by the generator set. In a preferred embodiment, the charge in the battery is supplemented by at least one solar panel adapted to supply charging current to the battery during daylight periods.

The electrical power supply system includes telemetry for sensing various parameters within a welfare unit incorporating that power supply system. The telemetry control system then transmits data to a remote location whereat the data is analysed and then signals are sent back to the welfare unit in order to control operation of at least the generator set. The remote location may, in the case of a self-contained welfare unit hired from a rental firm, be a server located at the rental firm so that the firm may monitor the usage of electricity, fuel for powering the generator set, water consumption and so on.

The rental firm may then also control the operation of the generator set to effect recharging of the battery, taking into account the data transmitted to the server and also other factors such as the hours at which work is being undertaken on the construction site, no operation during unsocial hours and so on.

The output of the generator set is used primarily to charge the battery but during periods of peak power demand by the welfare unit, the output of the generator set may supplement the power drawn from the battery by the facilities in the welfare unit. The maximum power output of the generator set should be just sufficient to ensure an adequate level of charge is maintained in the battery with only intermittent running of the generator set but when running the internal combustion engine should operate at a constant rotational rate, to obtain maximum efficiency. Advantageously, the generator set is arranged to run on LPG fuel drawn from a storage tank therefor.

This invention extends to a welfare unit comprising a waterproof enclosure containing toilet and washing facilities, a water supply installation including a water tank, a water heater and pipe work arranged to supply cold running water to the toilet and washing facilities and hot running water to the washing facility, a waste water storage tank and also an electrical power supply arrangement of this invention as described above.

The water heater of the welfare unit may be powered by at least one of electricity supplied by the feed unit and flammable gas supplied from a storage tank. Both the generator set and the water heater may draw flammable gas from the same storage tank.

Various sensors may be provided within the welfare unit to monitor parameters of the facilities, such as water usage, water heater operation, levels in the water tank and waste water tank and lighting operation as well as the charge level and the operation of the generator set, as described above. All of these monitored parameters may be sent back to the remote server and using that data, an operation profile may be modelled in order to minimise the consumption of electricity, and so also the operation of the generator set. Using the telemetry link, the generator set may be powered when required to maintain an adequate level of charge in the battery, while also eliminating operation during periods when the welfare facility is not in use or when work is not taking place on a construction site.

This invention extends to a method of operating a welfare unit according to this invention as described above, wherein the fuel consumption of the generator set is minimised while maintaining operational the facilities, by the steps of monitoring the battery charge level and the power demand of the welfare unit, transmitting data to a remote server, analysing the transmitted data, defining a control profile for the usage of the welfare unit, and transmitting back to the welfare unit appropriate control signals to implement that profile.

By way of example only, one specific embodiment of a self-contained welfare unit of this invention incorporating a power supply arrangement also of this invention as well as a method of operating the welfare unit will now be described in detail, reference being made to the accompanying drawings in which:-Figure 1 is a block diagram showing the operational outline of the embodiment; and Figure 2 shows the power system operation for that embodiment of welfare unit.

A self-contained welfare unit constructed and arranged in accordance with this invention typically employs a purpose built steel unit similar to an ISO container and including windows, doors, insulation and internal walls dividing the steel unit into the required room spaces for toilet facilities, washing facilities and perhaps also a rest-room and a kitchen area. The advantage of having a steel unit similar to an ISO container is that the finished welfare unit may easily be lifted and moved to and from construction sites using conventional container handling and transportation equipment.

The self-contained welfare unit must be capable of operating for a period of time providing the required facilities, without connections to mains water, mains drainage and mains electricity. The unit thus will include a fresh water tank together with pipe work leading to the toilet and washing facilities, a pump being arranged to supply running water at an appropriate pressure from the tank to those facilities. An accumulator may also be fitted to the water supply arrangement to minimise the frequency with which the pump operates. A suitable water supply arrangement is described and claimed in WO99/63225, this arrangement being configured to minimise the consumption of electricity by the pump and also to minimise any wastage of water.

The water supply arrangement for most welfare units currently in use are able to supply hot running water as well as cold running water. For this purpose, an instantaneous water heater may be provided, either gas-powered or (if mains voltage is available) electrically-powered. In the case of a gas water heater, the gas may be drawn from a bottle of compressed gas arranged externally of the unit and connected through a regulator to a gas pipe leading to the water heater. Gas may also be used for space heating, within the welfare unit.

If no connection to a mains drainage is available, then the unit requires a waste water storage tank which periodically must be emptied. Such tanks, including a disinfection arrangement, are well known for example in the caravanning and boating industries, as well as in known forms of self-contained welfare unit already in use.

An electrical supply for the unit is usually derived from a rechargeable accumulator, or a bank of such accumulators, both of which are herein referred to as "a battery". Typically, the output of such a battery is at I 2v or 24v and the pump of the water supply system may be designed to run on that voltage. From the health and safety point of view there are advantages in having the electrical supply at this low DC voltage, though the output of the battery may be supplied to an inverter such that the effective electrical supply to the unit is at 240v, 50Hz.

The precise constructional details of a self-contained welfare unit as outlined above are well known in the art and will not be discussed in further detail here, since those details do not form a part of the power supply system of this invention.

Referring now to Figure 1, there is shown in block diagram form an embodiment of the power supply system of this invention, as may be fitted to a self-contained welfare unit as described above. This power supply system includes a rechargeable battery 10 which in practice will be a bank of two or three lead-acid accumulators, preferably of the gel type, connected in parallel to have an output of 1 2v, or four accumulators connected in series and parallel to have a combined output of 24v. The output of the battery 10 is connected through a solid-state synchronous charger/inverter 11 which supplies 240v, 50Hz to a power feed and distribution unit 12. This distribution unit includes bus-bars, fuses or trips and residual current devices to give protection to the electrical installation which typically may include lighting, a water pump, instant water heating, cooking facilities (such as a kettle and microwave oven), space heating and so on.

A charging arrangement for the battery 10 comprises a generator set 13 and one or more solar panels 14, both of which are connected to the charger/inverter 11. During hours of sunlight, the solar panels will provide charging current to the battery 10, or may contribute to the total power drawn by the distribution unit 12, for supply to the facilities within the welfare unit. It is envisaged that the total power output of the solar panels will at certain times be insufficient to maintain an adequate charge within the battery 10 and then the generator set 13 may be operated to supply charging current to the battery 10 or contribute to the total power drawn by the distribution unit 12.

The synchronous charger/inverter 11 typically can take two different power sources, including AC and DC power sources, and provide a seamless power supply to electrical equipment drawing power at a predetermined voltage, such as 240v 50Hz. Often the power sources will be a generator and batteries and surplus generator power can be directed to the batteries to effect charging thereof. Though the charger/inverter may be used to combine the output of the two power sources to meet high demand, in this embodiment this is not done.

Rather, the inverter considerably limits the power output of the system even though the generator set 13 ma be capable of producing more power. The main purpose of the generator set is to charge the batteries and secondly to provide power should the batteries become flat. The limitation of the power output from the generator set is in particular to increase the efficiency of operation thereof. As the generator set does not have to accommodate surges in the power demand, it will not be working at maximum capacity and this creates significant efficiencies in fuel consumption and wear and tear on the generator set. In turn, this leads to extended service intervals and reduced the likelihood that engineers are needed to visit a unit when on site.

As the generator set 13 is intended merely to supply charging current, the internal combustion engine may run at a fixed speed and power output designed to give optimum alternator output so that the maximum energy is stored, for the amount of fuel consumed. This may be contrasted with a generator set able to provide the maximum power requirement of a welfare unit, where the generator set may idle for perhaps 85% of every day and produce significant electrical energy only occasionally.

The running cost of the generator set 13 may be reduced, and the service intervals extended, by powering the internal combustion engine of the -10-generator set on liquid petroleum gas (LPG) rather than petrol or diesel. The LPG may be stored in a tank 15, or in a bottle or a bank of bottles external to the welfare unit and connected through a regulator to the engine of the generator set.

As the electrical power supplied to the welfare unit by the charger/inverter 11 is at 240v, the generator set is protected against an overload condition at a time of peak power demand within the welfare unit and the 240v supply is protected against voltage variation. Further, the use of solar panels 14 to assist with the recharging of the battery gives an overall gain in the efficiency of the system.

The power supply system of the welfare unit, as described above, includes a telemetry control system 16 including sensors for battery voltage (or charge state), operation of the generator set 13, content of the LPG tank 15, operation of the charger/inverter 11, the electrical current flowing through the power feed/distribution unit 12 and further sensors to give operational monitoring of the power needs of the various electrical appliances and facilities arranged within the welfare unit, as shown at 17. Further sensors are provided for operation of the water heater 18 for the water supply system, as well as for water use in general, as shown at 19, and for the content in a waste water tank 20.

The telemetry control system 16 is arranged to transmit data to a remote server (not shown in Figure 2) where the transmitted data is analysed and then appropriate control signals are sent back to the telemetry control system 16, to control operation of the generator set 13 as well as the power feed/distribution unit 12. The telemetry control system may thus control startlstop cycles for the generator set, as well as the run-time, hours of operation during the day, set programmes of operation, monitor battery voltage and also issue alerts as required, for example if the water or LPG levels are getting low, or the amount of waste water stored in the tank 20 is becoming too great. The remote server may also remodel the operational profile of the welfare unit to suit the use of the unit by analysis of the data, so that the overall system appears to be "intelligent" to users of the unit, by adapting to changing use patterns and also to minimise fuel consumption.

Figure 2 is a simplified wiring diagram for the electrical power supply system for the welfare unit discussed above and the same reference characters are used for like components with those of Figure 1. In this example, there is shown a bank of three lead-acid gel batteries 10 connected in parallel and with the negative terminals of those batteries bonded to the shell of the welfare unit, as an earth connection 22. The parallel-connected positive terminals are connected through a high-current DC switch 23 to a 5kw charger/inverter lithe output of which is at 240v, 50Hz. This is fed along line 24 through a 30A isolation switch 25 to the distribution unit 12, which includes 5A and ISA miniature circuit breakers 26 for lighting and power sockets respectively.

The negative side of the batteries 10 are also connected to a bus-bar distribution panel 27 with the 12v positive supply being connected through a fused terminal block 28 to separately fused 12v circuits for example for the fresh water pump, the telemetry supply and other uses as required within the welfare unit. -12-

Recharging of the batteries is performed by a bkva, 240v generator set 13 having its own dedicated starting battery 29, recharged by a conventional alternator associated with the engine of the generator set. The main output of the generator set is supplied to the charger/inverter 11, either for battery charging or contributing to the overall 240v power demand of the welfare unit.

Further, a pair of solar panels 14 are connected through respective controllers and fuses 31 to the batteries 10 to supply charging current during hours of sunlight.

It will be appreciated that as compared to conventional self-contained welfare units, a welfare unit of this invention as exemplified above has the advantages that the unit has a greatly reduced fuel consumption and that the use of renewable energy is maxim ised. It also becomes possible to extend the useful life of the various components, and in particular of the generator set.

These advantages are reflected in the overall cost of the unit, or in the cost of hiring such a unit while providing to the ultimate user a cutting-edge environmental unit. -13-

Claims

CLAIMS1. An electrical power supply system for a welfare unit, comprising an electrical power feed unit arranged to feed electrical power to components in the welfare unit; -a rechargeable battery connected to the power feed unit; -a generator set including an internal combustion engine and arranged to charge the battery and supply electrical power to the feed unit; -a plurality of sensors arranged to monitor at least the state of charge of the battery and the power demand of the welfare unit; and -a telemetry control system receiving the outputs of the sensors and transmitting corresponding data to a remote location, and controlling operation of the generator set dependent on instructions received from said remote location.
2. An electrical power supply arrangement as claimed in claim 1, wherein the output of the generator set primarily to charges the battery but may supplement the power drawn from the battery by the feed unit during periods of peak power usage by the welfare unit.
3. An electrical power supply arrangement as claimed in claim 2, wherein the peak power output of the generator set is less than the peak electrical power demand of the welfare unit, fed through the feed unit.
4. An electrical power supply arrangement as claimed in any of the preceding claims, wherein there is a storage tank for LPG fuel and the generator set is powered by LPG fuel drawn from the tank. -14-
5. An electrical power supply arrangement as claimed in any of the preceding claims, wherein the telemetry control system functions to minimise the consumption of fuel by the generator set while maintaining an adequate charge in the battery.
6. An electrical power supply arrangement as claimed in any of the preceding claims and including a solid-state inverter arranged to supply alternating current electricity to the unit at the conventional mains supply voltage.
7. An electrical power supply arrangement as claimed in any of the preceding claims, wherein at least one solar panel is provided as a part of the power supply arrangement, and the or each solar panel being arranged to supply charging current to the battery during daylight hours.
8. An electrical power supply arrangement for a welfare unit and as claimed in claim 1, and substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.
9. A welfare unit comprising a waterproof enclosure containing toilet and washing facilities, a water supply installation including a water tank, a water heater and pipework arranged to supply cold running water to the toilet and washing facilities and hot running water to the washing facility, a waste water storage tank and an electrical power supply arrangement as claimed in any of claims I to 8 for supplying power to at least a pump for the water supply installation. -15-
10. A welfare unit as claimed in claim 9, wherein water heater is powered by at least one of electricity supplied by the feed unit and flammable gas from a storage tank.
11. A welfare unit as claimed in claim 4 and claim 10, wherein the water heater is powered by LPG drawn from the supply tank for LPG for the generator set.
12. A welfare unit as claimed in any of claims 9 to 11, wherein the power supply system includes a sensor for at least one of water in said water tank, waste water in the waste water storage tank, and available fuel for the generator set.
13. A welfare unit as claimed in any of claims 9 to 12, wherein the power supply system includes at least one further sensor to monitor water usage by the facilities of the welfare unit.
14. A welfare unit as claimed in any of claims 9 to 13, wherein the unit incorporates electric lighting powered by the electrical power supply system.
15. A welfare unit as claimed in claim 14, wherein a sensor for usage of the electric lighting is arranged to provide an output to the telemetry control system.
16. A welfare unit as claimed in any of claims 9 to 15, wherein the telemetry control system communicates with a remote server arranged to analyse the data sent to the server, and the server supplies information and alarms to an operator of the server about the functioning of the welfare unit and also supplies appropriate control signals to the telemetry control system of the welfare unit to control the operation of at least the generator set. -16-
17. A welfare unit as claimed in claim 16, wherein the server models a control profile for the welfare unit to suit the monitored use of the unit and sends appropriate control signals to the telemetry control system of the welfare unit to implement that profile.
18. A welfare unit as claimed in any of claims 9 to 17, wherein the unit is wholly self-contained and requires no connections to external water, drainage or power sources for normal operation.
19. A welfare unit as claimed in any of claims 9 to 18 and substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.
20. A method of operating a welfare unit as claimed in any of claims 9 to 19 and in which the fuel consumption of the generator set is minimised while maintaining operational facilities, by the steps of monitoring the battery charge level and the power demand of the welfare unit, transmitting data to a remote server, analysing the transmitted data, defining a control profile for the usage of the welfare unit, and transmitting back to the welfare unit appropriate control signals to implement that profile.