need assistance with a relay circuit.

Thread Starter

POWER NEW

Joined Aug 22, 2018
14
need assistance with a relay circuit.
Want to trigger a relay when the voltage drops on a 5HP Motor
By as much as 30 volts or by as much as 5 amp.


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Bernard

Joined Aug 7, 2008
5,656
Need more information but for now some speculation, motor 240 V AC. Use a 240 V to 12V transformer, full wave rectify & filter. Feed result to comparator with a reference so that comp. output goes high when signal falls to about 10V. A driver then closes relay.
 

Picbuster

Joined Dec 2, 2013
1,022
Indeed we need more information.
The circuit is simple however:
a: is the motor permanent switched off when situation occurs?
b:If so how to switch it on? (eq reset the status)
d:during startup high current and voltage drop is normal. detection of the unwanted situation has to postponed but for how long?

Picbuster
 

Thread Starter

POWER NEW

Joined Aug 22, 2018
14
more information.
Saw Mill
230 VAC 23 AMP 5 HP motor 3600 RPM
This motor is running off of a 240 VAC Generator
5 HP motor starts to slow down, this is where I need the circuit.
 

Reloadron

Joined Jan 15, 2015
5,646
If this is any sort of an industrial application there are transducers off the shelf which will monitor things like line voltage and motor current draw. They are designed to drop a motor or other load offline when the current exceeds a preset level or the line voltage drops below a certain level. A 5 HP motor has a starter contactor and when a preset voltage happens the contactor can drop out. How you reset is up to you. Something as simple as this for voltage monitoring.

Ron
 

Thread Starter

POWER NEW

Joined Aug 22, 2018
14
If this is any sort of an industrial application there are transducers off the shelf which will monitor things like line voltage and motor current draw. They are designed to drop a motor or other load offline when the current exceeds a preset level or the line voltage drops below a certain level. A 5 HP motor has a starter contactor and when a preset voltage happens the contactor can drop out. How you reset is up to you. Something as simple as this for voltage monitoring.

Ron
New
Thank you Ron you have give me what I needed. put you a 10+ for this.
 
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