WO2011121614A2

WO2011121614A2 - A control system of valves for transformer cooling by using relay system

Info

Publication number: WO2011121614A2
Application number: PCT/IN2011/000225
Authority: WO
Inventors: David G. Sanders
Original assignee: Crompton Greaves Limited
Priority date: 2010-03-31
Filing date: 2011-03-30
Publication date: 2011-10-06
Also published as: WO2011121614A3

Abstract

A control system of valves for transformer cooling by using relay system, said system comprising: a. first pump adapted to pump oil for cooling; b. second pump adapted to pump oil for cooling; c. first valve adapted to control flow of pumped oil from said first pump; d. second valve adapted to control flow of pumped oil from said second pump; e. first relay adapted to actuate said first valve; f. second relay adapted to actuate said second valve; g. valve operating state monitoring means adapted to monitor operating position of said first valve and said second valve; h. relay operating means adapted to operate said first relay and said second relay for controlling operation of said monitored first valve and said second valve; i. first oil flow monitoring means adapted to monitor flow of oil from said first pump; j. second oil flow monitoring means adapted to monitor flow of oil from said second pump; k. first energizing means adapted to energise first relay for actuation, if oil flow is not established at said first pump as monitored by said first oil flow monitoring means; and 1. second energizing means adapted to energise second relay for actuation, if oil flow is not established at said second pump as monitored by said second oil flow monitoring means.

Description

TITLE OF THE INVENTION A control system of valves for transformer cooling by using relay system.

This application claims priority from Indian Patent Application no 1020/MUM/2010 filed on 31^st March 2010.

FIELD OF INVENTION:

This invention relates to a control systems.

Particularly, this system relates to a PLC Control for Motorized Back flow Valves to provide a control system of valves for transformer cooling by using relay system.

BACKGROUND OF INVENTION:

Power transformers utilised throughout the electrical power generation, transmission and distribution industry are equipped with a variety of cooling systems designed to remove excess heat generated during transformer operations. Although these installed cooling systems typically have adequate cooling capacity to maintain transformer winding temperature within acceptable limits, auxiliary cooling may become necessary during periods of extreme environmental conditions and end / or abnormally high power loading conditions.

These auxiliary cooling systems may be employed to prevent heat related damage to transformer windings as well as to increase the working life span of transformer by reducing the time the transformer is operated at elevated temperatures.

Conventionally such auxiliary cooling systems consist of a basic heat exchanger that is either turned on/off manually or automatically by a conventional thermostat mechanism.

Also known in prior art is a fluid cooled power transformers often have one or more pumps which force the fluid coolant through radiators wherein some of the heat of the coolant is dissipated. In certain types of transformers, or in particular applications, one or more standby pumps are fixed to the transformer for use if the main pump fails. Switching from the main pump to the standby pump is usually accomplished automatically, often by the use of pressure or flow responsive control devices. To prevent the circulation of coolant through the non-operating pump and the resulting reduction in the efficiency of the cooling system, it has been common practice to install check valves in the flow paths of the main and standby pumps. Such valves permit the flow of fluid in only one direction, and thereby prevent circulating flow of coolant through the non-operating pump.

A system to control, protect and monitor the status of forced cooling motors for power transformers and similar, wherein conventional cooling motors are turned into "intelligent" motors, operating in a totally autonomous manner, whose electronic module is installed on the actual motor cover, more specifically on the connection box and interconnected by a- communication network to a digital system without the need to use any external control, protection and monitoring elements or exaggerated panels for functioning.

The contact and relays is adopted in electrical control circuit of existed transformer forced-oil-air cooling control system, with low reliability, little protection function, uneasily extended and no communication interface. The way that programmable logical controller (PLC) with high reliability and versatility replaces partial unreliable contact and relays to modify older system is presented, and a new transformer forced-oil-air cooling control system is designed. Its site operation shows that the device is of high operation reliability and control accuracy, has perfect functions and notable effect of power saving.

The use of PLC control in transformer cooling system exists in the prior art and also the use of PLC for monitoring and display of the status and alarm signals is known. The PLC for operating motorized valves without any relay system is disclosed in the prior art for automatic rolling mill cooling and lubricating control system application.

However, disclosure of control of motorized valves for transformer cooling is proposed and there is no prior art disclosure recites about the PLC for operating motorized back-flow valves by using relay system for transformer cooling. OBJECTS OF INVENTION:

An object of the invention is to provide a PLC Control for Motorized Back flow Valves to provide a control of motorized valves for transformer cooling for operating motorized back-flow valves by using relay system for transformer cooling.

An object of the invention is to provide a PLC Control for Motorized Back flow Valves, which can permits isolation of on-functioning piping / pump and maximise cooling.

An object of the invention is to provide a PLC Control for Motorized Back flow Valves, which can permits warning of cooling failure and indication of valve operation.

An object of the invention is to provide a PLC Control for Motorized Back flow Valves, which eliminates troublesome mechanical backflow valves allowing of greater reliability.

An object of the invention is to provide a novel adjustable motor mounting arrangement, which can be used for large power transformers with oil directed cooling.

SUMMARY OF THE INVENTION:

According to this invention, there is provided a control system of valves for transformer cooling by using relay system, said system comprises:

a. first pump adapted to pump oil for cooling;

b. second pump adapted to pump oil for cooling;

c. first valve adapted to control flow of pumped oil from said first pump;

d. second valve adapted to control flow of pumped oil from said second pump; e. first relay adapted to actuate said first valve;

f. second relay adapted to actuate said second valve;

g. valve operating state monitoring means adapted to monitor operating position of said first valve and said second valve;

h. relay operating means adapted to operate said first relay and said second relay for controlling operation of said monitored first valve and said second valve;

i. first oil flow monitoring means adapted to monitor flow of oil from said first pump;

j. second oil flow monitoring means adapted to monitor flow of oil from said second pump;

k. first energizing means adapted to energise first relay for actuation, if oil flow is not established at said first pump as monitored by said first oil flow monitoring means; and

1. second energizing means adapted to energise second relay for actuation, if oil flow is not established at said second pump as monitored by said second oil flow monitoring means. Typically, said first energising means is a time-based energising means adapted to be engaged upon expiration of set time.

Typically, said second energising means is a time-based is a time-based energising means adapted to be engaged upon expiration of set time.

Typically, said system includes means to remove signals to open said first valve if oil flow is established at said first pump and not at said second pump.

Typically, said system includes means to remove signals to open said second valve if oil flow is established at said second pump and not at said first pump.

Typically, said first timed contact is a timed contact on said first relay that will close and initiate the closing of said first valve.

Typically, said second timed contact is a timed contact on said second relay that will close and initiate the closing of said second valve.

Typically, said control system is a PLC based control system.

Typically, said system includes alarm and display means adapted to display monitored position of valves.

Typically, said system includes alarm and display means adapted to display monitored position of relays. Typically, said system includes locking means adapted to lock said first and said second relay. If both flow indicators are operated at the exact same time.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:

The invention will now be described in relation to the accompanying drawings, in which:

Figure 1 illustrates a schematic of the system.

DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS:

According to the invention there is a PLC Control for Motorized Back flow Valves to provide a control system of motorized valves for transformer cooling for operating motorized back-flow valves by using relay system for transformer cooling.

Figure 1 illustrates a schematic of the system (100).

Typically, said system includes a first pump (PI ) adapted to pump oil for cooling; second pump (P2) adapted to pump oil for cooling; first valve (VI ) adapted to control flow of pumped oil from said first pump; second valve (V2) adapted to control flow of pumped oil from said second pump; first relay (Rl ) adapted to actuate said first valve; second relay (R2) adapted to actuate said second valve; In accordance with an embodiment of this invention, said system comprises a valve operating state monitoring means (VM) adapted to monitor operating position of said first valve and said second valve and a relay operating means (RM) adapted to operate said first relay and said second relay for controlling operation of said monitored first valve and said second valve.

The system provides for monitoring the position of the Valves (open/close) by using flow indicators of the pumps. Also, PLC for operating of the relays that in turn operate the motorized valves and provides the alarm signals and displays the message based on valves position are provided.

In accordance with another embodiment of this invention, said system includes means to indicate an Isolation of non-functioning piping/Pump and maximize cooling and also permits warnings of cooling failures.

In accordance with yet another embodiment of this invention, said system is adapted to operate in Normal Stage (ONAN Natural Cooling), wherein the normal state Inputs to first Input and second Input will be powered. These signals come from the normally closed contacts of the oil flow indicators at the pumps. The powered state indicates that there is no oil flow. Inputs at predetermined inputs (on the PLC scheme) will be powered confirming from the valve limit switches that the valves are open and PLC will display the text "Normal both valves open".

In accordance with yet another embodiment of this invention, there is provided a means to provide two distinct functions to the PLC control; one is to operate the relays to operate the valves; and the second is to monitor the position of those valves and provide alarm signals based on those signals

In accordance with still another embodiment of this invention, said system includes first oil flow monitoring means (OM1) adapted to monitor flow of oil from said first pump; and second oil flow monitoring means (OM2) adapted to monitor flow of oil from said second pump;

When oil flow is established at first pump, the first input will de-energise from the action of the oil flow indicator. Similarly when oil flow is established at second pump the second input will de-energise from action of the oil flow indicator.

In accordance an additional embodiment of this invention, said system includes first energising means (EMI ) adapted to energise first relay for actuation, if oil flow is not established at said first pump as monitored by said first oil flow monitoring means. If oil flow is established at first pump and not at second pump, the PLC-VC will energise first relay. This will immediately close second valve, but will remove the signals to open the valve. If flow is not established at second pump within the time delay set on the second relay, a timed contact on second relay will close and initiate the closing of the second valve.

In accordance with yet an embodiment of this invention, said system includes second energising means (EM2) adapted to energise second relay for actuation, if oil flow is not established at said second pump as monitored by said second oil flow monitoring means. If oil flow is established at second pump and not at first pump, the PLC-VC will energise first relay. This will not immediately close first valve, but will remove the signal to open the valve. If flow is not established at first pump within the time delay set on the first relay, a timed contact on first relay will close and initiate the closing of first valve.

In accordance with yet an additional embodiment of this invention, includes locking means adapted to lock said first and said second relay. If both flow indicators are operated at the exact same time neither relay first and second would operate. This may be unlikely. To see a short time energisation of either first or second relay is expected. As long as the period between the flow indicators operating does not exceed the time delays at the relays first and second the motorised valves will not operate and will remain open.

When flow is established at both pumps there will be an isolated contacts closure at the terminals. This is a signal for customer's use that both pumps are operating.

In accordance with the present invention, said system includes valve monitoring system which limits switches on the motorized valve indicates the valve position. when first valve and second valve are signaling open, the PLC display "Normal both valves open"; when first valve starts to close the PLC display changes to show the PLC operating status. If the valve takes too long to travel between the open and close positions, alarm light (energised from the PLC output three) will start to flash and the PLC display will change to "first Valve High OPN-CLO Time" The will also be an isolated contact closure at terminals. This is a signal for the customer's use that there is a valve control failure. When valve q closes the PLC display will show "first Valve closed" and similarly functions exist for second valve;

If both valves are closed there will be a time delay to allow for valve travelling time. If that delay is expected alarm light (energised from the PLC output three) will start to flash and the PLC display will change to "Both valves closed alarm" The will also be an isolated contact closure at terminals. This is a signal for the customers use that there is a valve control failure.

Claims

We claim,

1. A control system of valves for transformer cooling by using relay system, said system comprising:

a. first pump adapted to pump oil for cooling;

b. second pump adapted to pump oil for cooling;

c. first valve adapted to control flow of pumped oil from said first pump; d. second valve adapted to control flow of pumped oil from said second pump;

e. first relay adapted to actuate said first valve;

f. second relay adapted to actuate said second valve;

1. second energizing means adapted to energise second relay for actuation, if oil flow is not established at said second pump as monitored by said second oil flow monitoring means.

2. A control system as claimed in claim 1 wherein, said first energising means is a time-based energising means adapted to be engaged upon expiration of set time.

3. A control system as claimed in claim 1 wherein, said second energising means is a time-based is a time-based energising means adapted to be engaged upon expiration of set time.

4. A control system as claimed in claim 1 wherein, said system includes means to remove signals to open said first valve if oil flow is established at said first pump and not at said second pump.

5. A control system as claimed in claim 1 wherein, said system includes means to remove signals to open said second valve if oil flow is established at said second pump and not at said first pump.

6. A control system as claimed in claim 1 wherein, said first timed contact is a timed contact on said first relay that will close and initiate the closing of said first valve.

7. A control system as claimed in claim 1 wherein, said second timed contact is a timed contact on said second relay that will close and initiate the closing of said second valve.

8. A control system as claimed in claim 1 wherein, said control system is a PLC based control system.

9. A control system as claimed in claim 1 wherein, said system includes alarm and display means adapted to display monitored position of valves.

10. A control system as claimed in claim 1 wherein, said system includes alarm and display means adapted to display monitored position of relays.

1 1. A control system as claimed in claim 1 wherein, said system includes locking means adapted to lock said first and said second relay. If both flow indicators are operated at the exact same time.