Motor pump starter connection with two relay to operate manual and auto

Thread Starter

sajsaj220

Joined Jan 17, 2020
5
Hi,
The ckt as as draw as attached, is a auto/manual control panel board for pump-motor and trying to configure to run with MCU control auto operation and manual (with start/stop button in board).
With the panel here i have included 2 nos relay: Relay-1, NO, parallel connected to START BUTTON and Relay-2, NC, series connected with STOP BUTTON for the purpose.
From the ckt, my perception is as follows:
1) Manual operation is found to be correctly.
2) For the case of auto operation: when relay-1 close, the loop of the COIL (CONTRACTOR) closed through Relay-2 and the COIL(CONTRACTOR) is energized, "R" is given to load-motor.
BUT the STARTING CAPACITOR not getting supply through Terminal-C2 of the START button in this arrangement of Auto mode. Then how "Y" will be provided to Motor..

Therefore my question is,
1) Is this connection is correct for the operation without that of starting capacitor arrangement??
2) If not How should I connect to provide phase to STARTING CAPACITOR to keep manual/auto both operation?
Thks..
 

Attachments

AlbertHall

Joined Jun 4, 2014
9,326
Methinks relay-1 should be two pole with 1 pole connecting S1 and S2 as you have it, with the second pole connecting C1 and C2.
 

Thread Starter

sajsaj220

Joined Jan 17, 2020
5
is it not possible only with those spdt relay 1& 2 ??
will the motor run with this bypass/without start-capacitor as per ckt??
tnx
 

AlbertHall

Joined Jun 4, 2014
9,326
It is not possible to connect the start capacitor only temporarily during starting with just one contact on that relay.

I don't know what will happen without the start capacitor but I presume it is essential to the thing going. Without it you might be able to get the motor running if you can spin it by hand.
 

Thread Starter

sajsaj220

Joined Jan 17, 2020
5
but the ckt has been connected and motor(3 hp, single phase, 230v) running without spinning of it. so how is it possible? any clues..
what DPDT u recommend , whereas i used here SPDT of 30A(T90 model).
And one more confuse of mine is, with the ckt are relays as well as manual push button carries the motor’s load current as well as inrush current? if not then can relays be reduced to 6amp rating ? as per my openion the relays and manual push buttons only providing contractor’s coils current
 

AlbertHall

Joined Jun 4, 2014
9,326
The starting capacitor is connected in parallel with the running cap so that may be enough to get the motor running, presumably depending on the motor load.
If the motor starts and runs correctly with this arrangement then leave it as is.
 

Thread Starter

sajsaj220

Joined Jan 17, 2020
5
hi,
will manual push button and as wll as both relays carryies full load/inrush current ?
if not then the relays can be used miniature type pcb relay (of 10a) instead of thet 30A (T90 MODEL). My motor pump will be submersible 3hp/5hp.
tnx for your reply.
 

AlbertHall

Joined Jun 4, 2014
9,326
hi,
will manual push button and as wll as both relays carryies full load/inrush current ?
if not then the relays can be used miniature type pcb relay (of 10a) instead of thet 30A (T90 MODEL). My motor pump will be submersible 3hp/5hp.
tnx for your reply.
With your original diagram the relay contacts will only need to handle the contactor coil current at 230V.
 

Thread Starter

sajsaj220

Joined Jan 17, 2020
5
tnx.
Should I use 3 relay, (1 for stop control-10A, 1 for S2-10A, and last 1 for C2-30A PCB type) wherein S2 and C2 point-connected relays(NO) will close and release time at 50msec to start the pump,
and stop-point connected relay(NC) at 50msec to close & release and closeto stop the pump from the MCU.
Target for using 3 relay is to operate start capacitor as 30Amp PCB type DPDT is not available in market.
If the openion of mine is correct, then operation at 50msec for all 3 different rated relay is correct from aspect of MCU. or opration time for S2 and C2 need to be at different duration of time.
tnx
 
Top