GB2165380A - Apparatus for controlling quantities - Google Patents

Abstract

Quantities such as the magnitude of a resistive load in the testing of an electric power generator set, in industrial processes, or in heat sources may for example be controlled. An encoder receives an instruction as to the quantity required, and produces a digital coded signal. A number of modules receive the signal from the encoder or from another module in series. The modules comprise blocks having terminals for receiving signals, a panel for transmitting signals, and relays for bringing quantities into use.

Description

SPECIFICATION Apparatus for controlling quantities Technical Field The invention relates to apparatus for controlling quantities, and is particularly concerned with the precise determination of the magnitude of a resistive load to be applied in the testing and proving of an electric power generator set. Such sets have to be tested periodically to check that they are up to standard as to the power generated and how they react to a change of load.

The invention is not confined to such an end use, but could be adapted to the control of industrial processes or the operation of warehouses involving the use or measurement of accurately predetermined quantities of liquid, powder or grain, or to a highly controllable heat source for example.

Background Art In the testing of electric generators, it is required to be able to apply and vary a large resistive load very quickly so that the efficiently of a generator can be measured. Thus is has been known to lower electrodes into a tank of electrolyte and gauge the magnitude of the resistance introduced into circuit by measuring the length of the electrodes immersed. This is inaccurate, dangerous, and difficult to utilize particularly when the generator is inaccessible, for example on the roof of a building.

The Invention The invention provides apparatus for controlling quantities which comprises an encoder for receiving an instruction as to the quantity required and producing a digital coded signal, and a number of modules for receiving the signal from the encoder or from another module in series therewith, the modules comprising a block having terminals for receiving signals from the encoder and other terminals for receiving signals from another module in series therewith, a panei for transmitting signals to another module, and relays for bringing the appropriate quantities into utilization.

The instruction may be digital or decimal, and the coded signal may express the quantity as a sum of a number of integers. 1, 1, 3 and 5 are the preferred integers from which large numbers may be made up, but other combinations of integers such as 1, 2, 4 and 8 may be used instead. For larger numbers ten-fold and/or hundred-fold multiples of these integers may be used, and for smaller numbers fractions of these integers such as tenths may be used.

The encoder may include re-settable switches so that the module can change from one load to another by switching ON or switching OFF only those resistors necessary for making the change. The instruction may be introduced through a thumbwheel switch in respect of each digit in the quantity required. Alternatively, it may be introduced through solid state circuitry, for example a programmable logic controller, each digit energizing the appropriate output lines.

The encoder may be remote from the modules or may be housed in a space provided therein.

Any number of modules may be connected in series so that the apparatus can control the quantity desired with great precision. For example the load applied in the testing and proving of a generator set may be adjustable in steps 1 kw up to full capacity. Standard apparatus units of 100 kw and 200 kw capacity for example may be manufactured, and kept of sufficiently light weight to be maintained. Each module or load bank may be operated by its own encoder, or up to 1000 kw made up of 100 kw and 200 kw combinations may be connected by a common control looping from one another and serviced by one single encoder. This will give load adjustment from zero to 1000 kw in 1 kw steps.

The control circuit voltage may be derived from an alternator to which the module is connected or via an external source and is interlocked with a cooling fan and/or heat sensors. Each module should preferably contain as resistors horizontally mounted heating elements fitted with cooling fins and grouped to provide loading of 50 kw, 30 kw, 2X 10 kw, 5 kw, 3 kw and 2X 1 kw.

Drawings Fig. 1 is a schematic diagram of an encoder, being part of an apparatus according to the invention, Figure 2 is a diagram of a thumbwheel switch, three of which appear in Fig. 1, Figure 3 is a circuit diagram of a printed circuit board (control side) of the encoder of Fig. 1, Figure 4 is a diagram of a printed circuit board of a module for receiving signals from the encoder of Fig. 1, and which also is part of apparatus according to the invention, Figure 5 shows the circuit of the module of Fig. 4, and Fig. 6a is a plan section through the apparatus itself on A-A through Fig. 6b, Figure 6b is a side view of the apparatus, Figure 6c is a rear view of the apparatus, and Figure 6d is a front view.

Encoder Fig. 2 shows a thumbwheel switch T through which a single digit, whether of units, tens, hundreds or other magnitude may be introduced into the encoder. These figures could be adapted to other absolute values or the number of switches increased so that larger numbers of units such as thousands or smaller such as tenths, could be used. The digital or decimal setting of the thumbwheel switch as indicated near the bottom of Fig. 2 is converted into a coded value in which it is expressed as a sum of 1, 1, 3, and/or 5 units, the outputs of which are identified as a, b, c, d, respectively. For example, the digital value '7' is 1+1+5 in the code, and is represented by outputs on lines a, b, and d.For other values the coding is as follows: Digital Value Code Value Conducting Line Outputs Diodes 1 1 - a 2 1 + 1 D1 a.b 3 3 c 4 3 + 1 D2, D6 c, a 5 5 - d 6 5 + 1 D3, D10 d, a 7 5 + 1 + 1 D9, D5, D1 d, a, b 8 5 + 3 D7, D8 d, c 9 5 + 3 + 1 Dull, D4, D2, d, c, a D6 By moving a thumbwheel rotor e to the value '7' mentioned above, it can be seen that current is passed through conducting diodes D9, D5, and D1, and passed to line outputs d, a, b, respectively. For other numerical values other conducting diodes are connected as indicated each with an initial D.

In Fig. 1, the diagram of the encoder as a whole, three of such thumbwheel switches T are provided centrally for the input of the desired digital figure in hundreds, tens and units respectively from left to right. The thumbwheel switches T are each connected to four output relays referenced with the initial letters RL followed by C for hundreds, X for tens, and I for units, and then by 1A, 1B, 3 or 5 to indicate the coded value of the load which is to be utilized. Each of the relays is further marked with a numeral 1 to indicate that it is a single pole high speed bistable device providing a volt free output. The contacts of the outputs relays RL close on receipt of a positive output which is controlled by operation of an ENTER key. Operation of a CLEAR key applies a positive signal to the reset coils of the relays.

To the right of Fig. 1 there is shown a power source comprising a 9 volt battery marked 9v BATT which feeds the thumbwheel stitch rotors e through the ENTER key. After pressing the ENTER key, the thumbwheel switches T are set to a desired load value for a new program by a circuit in the top right hand corner of Fig. 1. The 'set' coils of the required relays selected from RLC1A etc by the thumbwheel switches T are energised, and at the same time a 5 ms pulse is applied to the reset coils of all those relays via a high speed reed relay CLR and associated components D14, Cl, C2 and R1. C1 determines the duration of the pulse, C2 provides a discrete supply reservoir for CLR/C1 via the ENTER key, and D14 decouples from the negative bus. Relays having a 'set' and 'reset' signal applied simultaneously will not change state, so all other than those from the old program which are required for the new will either be in or take up a reset state. After 5 ms, the relays CLR releases and removes the reset signal, allowing those relays in receipt of a 'set' signal to retain or take up the set positions and so complete the desired new program. Thus updating is achieved with minimum of disturbance, the required elements of the old program being retained, the redundant elements reset, and only new elements called up.

Energy is consumed only during a program enter or clear operation. If a program is entered as a 'preset' value before power is connected, the 9v BATT supplies the unit. 12 v DC control supplies of the load modules take over as soon as AC power is supplied, diodes D12 and D13 performing the switching function.

Module The lower part of Fig. 1 shows how each of the relays RLC1A etc is connected to one of the terminal pins 1 to 14 of a 26 way plug from the encoder which is fitted into a corresponding 26 way socket in a module (Fig. 5). The module connected to the encoder functions in a master mode. The terminal pins 1 to 14 are connected to a terminal board master control TBMC as shown in Fig. 4. The module also has a 12 pin slave output socket connecting terminal pins 15 to 25 of its input socket to the 26 pin control input socket of a downstream module operating in a slave mode (TBMC terminals 1 to 9). In slave mode, the modules are required to switch in 100 kw steps only, and the 1, 1, 3 5 kw facility is not utilised. The 10, 10, 30, 50 kw are collectively switched as a 100 kw step. The connection of a terminal board output TBOP in Fig.

5 is shown in detail in Fig. 4. Individual terminal pins of the terminal board master control TBMC and terminal board output TBOP are connected together and feed a hundreds decoder unit shown lower down in Fig. 4.

The hundreds decoder comprises relays RH1, 2, 3 and 5 and diodes D6 to D12, and its purpose is to convert the coded 'hundreds' signal into a cumulative 100 kw 'stepping' signal and apply it to the slave output socket via terminal block output TBOP. This achieved as follows:: Numerical Coded Relay Conducting Signal Out Value Relays Contacts Diodes TBOP Nos 100 RH 1 RH1-1 D11 1 200 RHi + RH2 RH1-l + Dll + D6 1-2 RH2-2 300 RH3 RH3-1 D7 + D6 1-3 400 RH3 + RHi RH3-1 + D7 + D6 1-4 RH1-2 500 RH5 RH5-1 D12 + D8 D7 + D1 1-5 500 RH5 + RHi RH5-1 + D12, D8, D7 1-6 RH1-3 D6 700 RH5 + RHi RH5-1 + D8, D7, D6, 1-7 RH2-2 Dull, D12, D9 800 RH5 + RH3 RH5-1 + D12, D7, D6 1-8 RH3-2 D10, D9, DS 900 RH5 + RH3 RH5-1 + All Diodes 1-9 +RH1 RH5-2 + RH3-3 + RH3-2 + RHl-l Relays RL1 to RL50 are single pole relays interfacing the output of the encoder unit directly with load contactors LC1A to LC50. Relay RL 100 is similar but only fitted to the 200 kw module and interfaces the 100 kw load contactor LC100 with the 'hundreds' decoder. The load contactors function merely as switches, and in adaptations of the invention other than the testing of electric generators would be used to operate solenoid valves or the like to allow the passage of a predetermined quantity of liquid for example in the control of an industrial process.

As shown in Fig. 5, the load contactors LC 1 A etc apply corresponding resistor elements indicated by rectangles to poles L1, L2, L3 and LN of a three phase electric generator via voltage selection links LK1, LK2 or LK3.

To the right of Fig. 4 is a stabilized power supply unit producing 12 v DC for powering code changes as explained above. This comprises a rectifier REC-1 and components R3, C4, C3, RL, RY1 and voltage stabilizer unit VSU. At the top left of Fig. 4, a printed circuit board PCB track switch is shown for setting as either a 100 kw or a 200 kw module. A 'first' 100 kw call up signal on TBMC-1 is routed to diodes D1 to D4, and causes relays RL10 to RL50 collectively to switch 100 kw. A 'second' 100 kw call up signal (TBMC-2) is routed to TBOP terminal 1. Any further call up signal is transferred to TBOP, and reduces the modules slave output signal by 100 kw.For a 200 kw setting, the 'first' 100 kw is supplied through relays RL100, and the second through relays RL10 to RL50. The terminal connector TBOP is set one position higher when functioning as a 200 kw module so as to correct the slave output call up signal by the additional 100 kw of load contribution.

A control loop switch S1 at the top left of Fig. 5 is closed on the final slave module in use in order that tens switching facility on the module in master mode forms the last 100 kw of load.

If there is no slave module, the switch S1 on the master module is closed. Thus, the first call up on the final slave module energises a line x and causes a diode D5 on the master module to turn on and bring in its tens facility as a 100 kw step.

Fig. 5 includes an auxiliary electric power input socket A through which a fan F can be driven if desired, being brought into operation by a switch S2.

Apparatus Two resistor elements are shown schematically in a chamber C in the plan view of the apparatus in Fig. 6a, in fact the chamber would be filled with such elements. The elements are cooled by the fan F. To the left of Fig. 6d are a housing E in which the encoder can be removably located, and in which the encoder is shown with a facia D having the three thumbwheel switches, the ENTER button and CLEAR button. To one side of the chamber C (below in Fig. 6a) is an element connection area, and adjacent a control gear area.

Claims (9)

1. Apparatus for controlling quantities which comprises an encoder for receiving an instruction as to the quantity required and producing a digital coded signal, and a number of modules for receiving the signal from the encoder or from another module in series therewith, the modules comprising a block having terminals for receiving signals from the encoder and other terminals for receiving signals from another module in series therewith, a panel for transmitting signal to another module, and relays for bringing the appropriate quantities into utilization.

2. Apparatus according to claim 1 in which the coded signal expresses the quantity as a sum of a number of integers.

3. Apparatus according to claim 2 in which the integers are 1, 1, 3 and 5.

4. Apparatus according to claim 3 in which multiples of the integers are used.

5. Apparatus according to claim 4 in which fractions of the integers are used.

6. Apparatus according to any preceding claim in which the encoder includes re-settable switches so that the module can change from one load to another by switching ON or switching OFF only those resistors necessary for making the change.

7. Apparatus according to any preceding claim in which the instruction is introduced a thumbwheel switch in respect of each digit in the quantity required.

8. Apparatus according to any preceding claim in which the instruction is introduced through solid state circuitry, for example a programmable logic controller, each digit energizing the appropriate output lines.

9. Apparatus for the determination of the magnitude of a resistive load as herein described with reference to the drawings.