need assistance with a relay circuit.

Discussion in 'The Projects Forum' started by POWER NEW, Nov 8, 2018.

  1. POWER NEW

    Thread Starter New Member

    Aug 22, 2018
    14
    0
    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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    Last edited by a moderator: Nov 9, 2018
  2. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,922
    541
    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.
     
  3. Picbuster

    Active Member

    Dec 2, 2013
    813
    100
    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
     
  4. Metalica

    Member

    Aug 1, 2010
    17
    0
    I wonder why you want to switch it off?
     
  5. POWER NEW

    Thread Starter New Member

    Aug 22, 2018
    14
    0
    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.
     
  6. MaxHeadRoom

    Expert

    Jul 18, 2013
    16,194
    4,745
    Is this due to a voltage drop or frequency drop?
    Max.
     
  7. POWER NEW

    Thread Starter New Member

    Aug 22, 2018
    14
    0
    This due to a voltage drop.
     
  8. Reloadron

    Distinguished Member

    Jan 15, 2015
    3,612
    1,620
    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
     
  9. POWER NEW

    Thread Starter New Member

    Aug 22, 2018
    14
    0
    New
    Thank you Ron you have give me what I needed. put you a 10+ for this.
     
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