Jump to content

Installation Trips

Recommended Posts

The EMX series soft starters include a test at start to ensure the integtrity of the starter and installation. If there is a problem found, the starter will not attempt a start, rather it will trip on installation fault.

The cause of the problem can be either internal to the starter or external, in the installation.

Fault finding:

  1. Ensure that there are no short circuits between input and output on any phase of the soft starter. If there is a shorted phase, there is a failed SCR.
  2. With the motor connected to the output of the soft starter, apply voltage to the input terminals (L1, L2 L3)
  3. Measure the voltage between input and output on each phase.(L1 - L4, L2 - L5, L3 - L6) If the starter is three wire connected, the voltage should equal the phase to neutral voltage for the supply and all three phases should be equal. If the motor is six wire connected, the voltage should be phase to phase voltage and be equal.
  4. If the voltage on any phase is zero, then check the incoming voltage on the supply.
  5. If the supply voltage is balanced, and the measured input to output voltage is unbalanced, then there is either a leaky SCR, or a pcb fault.
  6. Disconnect the inputs and outputs from the starter and use a 500volt insulation tester (megger) to measure between the input and output on each phase. The reading should be in the order of 33K. If there is a higher reading, then the control pcb is at fault, or there is a bad connection between the control pcb and the SCRs. If the reading is less than 33k, then an SCR is probably leaky.
Link to comment
Share on other sites

  • 14 years later...

Over the years since the release of the EMX3, we have experienced increasing problems of installation trips due to bad harmonic voltages.

Severe harmonic currents on weaker networks, primarily due to the major increase in usage of VFDs in industry has resulted in increasing levels of voltage distortion and that voltage distortion, if it is bad enough, can disturb the synchronisation of the SCR control circuits to the supply voltage zero crossings. The phase modulation of the voltage reference causes the installation trip.


This is just one of the consequences of rising harmonic voltages on the supply.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Create New...