Arranging Alarms for Tripping Motors

Does your control panel have a tripping lamp indicator and what is the lamp voltage. If you control panel have these motor tripping lamp indicator then it will be a easy circuit to design and the component used will be less

Hello Jraef:

You're a wealth of information about these newfangled gadgets. I would've merely used a contractor with an auxiliary contact to set off an alarm. Definitely better to find the problem before it occurs.

As simple as this will work.

I don't see how that is going to solve anything. From what I see there, it is for a small 1 phase motor and whenever the motor draws current, the buzzer will go off. What value does that offer other than being very annoying?

JRaef with due respect,

I am not here to defend my GA, Neither I do say that none of other answer offer any value, But at the same time we should look in to precision of answer with ref to what OP is asking for.

We don't know how frequent is tripping of motor, may be its once in a 15days.If that is the I case I don't see any reason to replace motor anyway.

You wrote,

it is for a small 1 phase motor and whenever the motor draws current, the buzzer will go off. What value does that offer other than being very annoying?

No, it can be used in three phase motor of any size, Three phase motor don't require a three phase alarm.And its not whenever motor draw current buzzer will go off, Infarct its whenever motor stop drawing current buzzer will go on, and then its going to annoy, Isn't that what OP want?

Regards.

Once a trip has operated and an alarm is active, the process is in peril.

The question needs alternative consideration.

• What things need to be done to the equipment to minimise the risk of a trip operating and an alarm being raised so that the process continues without peril?

This is a subject for discussion at a HazOp study, in the simultaneous presence of process people, operations people, instrumentation people, mechanical people, and can only be done locally.

The correct method is using thermistors for LV motors and for HT Its different.I presume u are refering to a low voltage motor.Motor manufactures can supply motors with thermistors .Now a motor with class B insulationr made for an ambient temp of 40Deg C (In India Its 50)the permitted temp rise is 80 Deg C Over 40Deg C Amb making the total to 120Deg C.Class B max temp allowed is 130DegC with 10Deg C reserved for hot spots.Normally 2 sets of thermistors 2 per phse are embedded in the windings one one for 120DegC and One for110DegC.It comes with a small relay which can be mounted on the panel.At 110Deg u will get the alarm and can take action to reduce the temp by redusing load If alarm is over looked at 120DegC it will trip the motor and prevent burn out.there are 2 types of thermistors possitive temp coefficient and negative temp. coeff.Each Phase we need 2 nos.It also comes with a simple realy having 1no+1NC Contact.If your existing motor does not have it you can procure it with the realy and embed in the over hangs of the stator winding and connect the realy suitably.

If you have the system designed properly,( correctly sized motors, correct impellers, etc.) the tripping of the motors and circulation pumps should not occur that often. Tripping can only happen unless there is a power fluctuation or a voltage drop. An alarm system will not be of much help because the motors have already stopped and the operator will still have to restart the system. But before you resume to operate, it is still a proper procedure to determine what has caused the tripping.

Hello Guest:

Several workable suggestions have been made. If you could please provide a little bit more information such as are these three phase motors or single phase and what type of budget are you trying and stay in. It might help to decide the best solution for you.

A kiss principle solution if they are three-phase and controlled by a mags would be to install a auxiliary contact on the Mag or it might already be present and use that contact to trip your alarm circuit.

This is a very simple circuit and requires no electronics. You merely route the power for your alarm through a dry contact.

In the alternative there are combination current sensors/contacts available. A little more expensive but will work with single phase or three-phase and very simple to install. The link below will take you to an example of one.

http://www.grainger.com/Grainger/items/6C057

This has several advantages over some of the other solutions. It can be programmed to trip below your anticipated overload current and thus provides you advance warning.

One of the workable solutions offered would have you build a custom circuit, in my opinion it's always better if possible to go with off-the-shelf products, you may understand the custom circuit however if you're not available the next repair tech may not.

These current sensors are extremely simple to install, merely route one of the current carrying conductor's that is going to your motor through the loop. Provide the sensor power supply (they are available in various supply voltages) and connect your alarm through the dry contacts provided on the sensor.

Since there are many other ways to do this additional information may provide you with a better solution, any of us can provide you with a wiring diagram.