Incoming supply is from city power. So electrical interlock is also not possible. Only option may be to used DS with earth position. Appreciate your response.
I am sorry the attachment was not included. Please have a look now.https://files.engineering.com/getfile.aspx?folder=e0c9aa6f-c095-4001-adf0-eb603067ac15&file=Earth_switch.pdf
I have seen earth switch (ES) on the 33kV incomer cubicle of the switchgear. It may be a requirement for the supply authority to ensure no power will be fed back during maintenance etc. My question is how to provide interlock to ensure the ES will not be operated while incoming supply is...
My object is data transfer between three pump stations and central SCADA station using GSM network. I came across SINAUT MICRO SC - software together with GSM Modem MD-720-3 which i feel is very close to my expectations.
What i am not sure is, whether static IP will be required for the...
Hi djs,
The make of the other PLC is not decided yet It has to be through competitive bidding and therefore it may be any make. Actually that is the main issue.
Hi djs,
The SCADA will be connected to other PLC as well, within the water treatment plant and secondary pump stations. I will upload a system diagram which gives more information.
Please have a look...
Hi djs,
Thank you for the reply.
The SCADA side equipment are not yet decided, and will be decided after tendering.
The target is to finish with the first guy and have everything ready for the second guy to move forward with his work without interaction with the first guy. (but seems...
Hi IRstuff,
Thank you for the reply. I take ICD as a good idea to start with. Regarding the protocol the first guy has agreed to go with any common one, but i will not know the preference of the second guy. However i do not think it will be a serious issue if common one is selected.
I am...
Hi,
I am involved with a project where information from an existing PLC is to be taken for the purpose of monitoring by a SCADA system. Basic information are indicated below,
Existing PLC - Siemens SIMATIC
Application - Filter control of a water treatment plant
Initially we planed for using...
The power factor we measureement with standard PF meter makes use of displacement of voltage and current phases, and when we measure PF with such meter, we observe good power factor for VFD drive. Or even leading PF due to the DC bus capacitors. However due to the harmonic currents generated by...
Hi all,
Thank you for all who have given comments.
It is good advise from JJPellin not to go for "smallest, fastest, largest or longest of any particular technology"
It is applicable in this case.
River sand is a problem for vertical turbine pumps, but main option we consider is vertical shaft...
Hi all,
Decision between submersible and vertical turbine pumps for raw water pumps has been discussed under thread 407-233951.
But my problem is more towards high capacity end in the region of 1250 L/S at 40M. (750kW)
Decision is almost made in favor of vertical shaft driven pumps, mainly...
waross (Electrical) 21 Jun 12 5:54
Try checking the efficiency without the VFD in the circuit.
There is no bypass contactor- The contractor is not ready to do a temporary wiring. So it is difficult. .
DRWeig (Electrical) 21 Jun 12 8:50
I'll amplify waross' second statement: Pump...
Hi Friends,
I have a question regarding the overall efficiency of VFD Driven motors. Normally the VFD efficiency is around 96% and motor efficiency around 94% (around 30kW range).
When we made a measurement for a motor used in pumping system, the overall efficiency fell much below the...
Thank you for all the voluble contributions made to this thread.
“Why do you feel the need for a contactor at all?” – I really do not have an answer other than that I have seen it as a practice.
Deep discharging of the capacitors seems to be the issue, as high inrush current is generated...
I have a problem with selecting between available variable speed dive wiring diagrams especially the location of the main contactor, as indicated below,
1) No contactor- drive is between the feeder MCCB and the motor. This is the simplest.
2) After the feeder MCCB before the VFD- Has the...
I wish to thank you for all the information. As dpc pointed out, in most cases there will be protections upstream. Undervoltage suggested by davidbeach is fail safe, but will need resetting after power outage.(i think) So it is a matter of choice considering the circumstances.
I have come across many earth fault protection arrangements, where the shunt trip of the MCCB along with an earth fault relay is used to isolate a circuit with earth fault. This arrangement is not fail safe for the following,
1) Power supply for the micro relay / earth fault / shunt trip is...
The requirement is to prepare an estimate for MCC's based on international rates. We already have prices from the local company. For other items such as PLC's prices are available in sites such as RS Components. VFD's now becoming more common i thought there may be similar sites. I was wrong.
