Internet PLC Forum

Hi,

I'm after some advice.  I'm looking to use the new F series when it arrives in the UK for a circuit breaker load shedding controller.

The general control is as follows, in the below example I'm using one generator with five load circuit breakers.  Each of the circuit breakers will have a power meter attached to the outgoing circuit.

The load (kW) will be read from this meter via modbus or the analogue inputs and stored in DM.  I will need create an average value from this reading so I know the load through the breaker.

EXAMPLE

1. ONE GENERATOR ON SITE GEN FRAME SIZE 1000KWe
2. AVERAGE SITE LOAD = 1350KWe
3. FIVE LOAD SHEDDING BREAKERS, EACH WITH 270KWe LOAD
4. EACH CB HAS A PRIORITY LEVEL 1-5, 1 BEING HIGHEST PRIORITY.



BLACK START - Mains failed

Input GEN ONLINE = 0
Input LOAD SHED = 1

1. LOAD SHED SIGNAL RECEIVED FROM CONTROL SYSTEM
2. ALL LOADS DISCONNECTED
3. CONFIRMATION SENT BACK TO  WITHIN 500MS
4. GEN ONLINE SIGNAL RECEIVED
5. 1ST PRIORITY LOAD STEP CB IS CLOSED (PRIORITY CB # 1 = 27OKWe 27% OF GENERATOR CAPACITY)
6. CALC IN PLC:- NEXT PRIORITY CB # 2 = 270KWe, ADD THIS TO EXISTING LOAD = 540KWe... 54% OF GENERATOR CAPACITY, IS THIS LESS THAN
SETPOINT (85%) IF YES MOVE TO NEXT STEP. IF NO, NO MORE LOADS CAN BE ADDED.
7. YES - ALLOW CLOSURE OF PRIORITY CB # 2.
6. CALC IN PLC:- NEXT PRIORITY CB # 3 = 270KWe, ADD THIS TO EXISTING LOAD = 810KWe... 81% OF GENERATOR CAPACITY, IS THIS LESS THAN
SETPOINT (85%) IF YES MOVE TO NEXT STEP. IF NO, NO MORE LOADS CAN BE ADDED.
7. YES - ALLOW CLOSURE OF PRIORITY CB # 3.
6. CALC IN PLC:- NEXT PRIORITY CB # 4 = 270KWe, ADD THIS TO EXISTING LOAD = 1080KWe... 108% OF GENERATOR CAPACITY, IS THIS LESS THAN
SETPOINT (85%) IF YES MOVE TO NEXT STEP. IF NO, NO MORE LOADS CAN BE ADDED.
7. NO - DO NOT ALLOW CLOSURE OF PRIORITY CB # 4.
8. CALC IN PLC RUNS CONTINUOUSLY TO SEE IF LOAD HAS CHANGED, IF LOAD IS REDUCED CB# 4 MAYBE ALLOWED TO CLOSE, IF THE EXISTING LOADS
INCREASE PAST THE SETPOINT CB # 3 WILL OPEN.
LOAD SHED SIGNAL REMOVED, MAINS RETURN SITE IN PARALLEL

Mains Returns

Input GEN ONLINE = 1
Input LOAD SHED = 0

9. ALL CLOSED LOAD STEPS REMAIN CLOSED.
10. REMAINING LOAD STEP CB'S ARE CLOSED
11. SYSTEM IS RESET.

MAINS FAILS WITH GENERATORS RUNNING

Input GEN ONLINE = 1
Input LOAD SHED = 1

12. OPERATION AS BEFORE HOWEVER IT WOULD BE NICE TO SPECIFY THAT AL LEAST 1 or 2 PRIORITY CB'S REMAIN CLOSED.
13. MAINS RETURNS. OPERATION AS BEFORE.

I was thinking of using three sequences, one for the "black start", one for the "mains returns" and one for the "mains fails with generators running".

Each sequencer will be enabled or disabled from a call function based on the inputs "gen online" and "load shed"

Do you this this is the best way to control this? can you suggest how the call functions and the sequencer functions would interact.

Many thanks.
   

Hi,

I Have two issues with the MDS100-BW.

A little history....

I'm using the TMD2424 to collect data from modbus devices on comm 3, display some info on the MDS100-BW also on comm 3.

Comm 1 is listening as a modbus slave.

1.  I'm using the MDS100-BW at 38400 baud no problems,  when I try to use 9600 baud the MDS100-BW screen doesn't  display any of  my messages.  I have set the jumper on the back and tried this on two MDS100-BW's both behave the same. I need this at 9600 baud as below.

2. I'm using comm 3 to communicate to a modbus device using the readmodb2, unfortunately this device is limited to 9600 baud, but this works fine.

Can I use the MDS100-BW also on comm 3? When I set the comm 3 baud to 38400 the display is garbled when I enable the readm2 command.

Do I need to give the MDS100-BW an ID number and use net commands instead of the Print #3 Function?

Can I use Comm 3 as a modbus master and hang the MDS100-BW display on the RS485 at the same time?

If not I could be in trouble!

Cheers

Hi,

I want to use the T100MD-2424 as a remote modbus master on one of the communication ports to collect some values and store them in DM

• .

On the other port I want the T100MD-2424+ to act as a MB slave so I can collect data from multiple T100MD-2424 that I have in the field.

Looking on your website, you indicate this is possible but I cannot find any further information in the manuals?  Is this possible?

Cheers

Hi,

Are the MDS 100 mounting holes and LCD position dimensions the same as the LCD 420?

Thanks

Hi,

I would like to create an alarm list utilising the MDS display, when I generate an alarm i.e. input 1 = CB trip. I want to display the message on the MDS display, this works however,  I have to specify what  line on the LCD the text is displayed, therefore I can only specify four alarms, one on each line.

Is it possible to have each alarm displayed on different lines on the LCD display as an active alarm list? when each alarm is cleared the list moves up one line.

Alternatively if I assign each alarm a DM value and use a simple program to display the text for that value i.e. DM[1]10 =  LCD text "Alarm",  DM[1]11 = LCD text "Trip", DM[1]12 = LCD text "Error" etc,  I still have the problem of having the active alarms displayed on multiple lines.

Any Ideas?

Kind regards.

Hi,

Can you tell me if its possible for a modbus master to change the timer settings, read I/O condition within the ladder program?

i.e. change timer "t1" from 100 to 1000  and read or write inputs / outputs from a touch screen HMI as the configured as the modbus master.

Many Thanks

Marcus