Hi I’m trying to understand the physics of a transformer with the secondary short circuited. When it’s shorted I’ve read something about the current decreasing in the secondary and rising in the primary what causes this?
I’ve got a temporary 22Kw motor running on a 63amp isolator. Think the isolator is rated AC3 for 11Kw . If the isolators not being used to switch the load is this okay?
I’m trying to answer a question relating to tensile testing and how the results from the test would differ from theoretical. I’m thinking temperature but I’m not sure if there is something more obvious I’m missing?
I’ve been trying to understand inductive loads and voltage drop. I though if voltage drops on an inductive circuit the current will also decrease. Is this correct? I understand if on phase of a 3 phase motor circuit one phase is high resistance this causes an imbalance causing the other two...
hi guys I'm trying to get my head clear on transformer winding polarity on a three phase transformer. what are the effects of one winding having an incorrect polarity wrt the other 2. I know the phase relationship will change but physically what will happen?
many thanks for your in-depth...
say if you have a motor circuit fed by 100amp fuses then then the overload set at 75 amps does this mean the motor cable should be rated for 100amps or should it be rated at 75amps?
What losses do we have in a pure sine wave inverter an I right in saying we’d have losses from the transistors. And from the internal transformer? I’m trying to work out what effects the efficiency of these.
Hi again guys I’m trying to get my head around the efficiency of generators. I’m looking at car alternator and can see this is an AC machine that then used a bridge rectifier to convert to DC this is where I’m thinking most of the efficiency is lost but want to understand in more depth?
Does the added resistance in these motors on start up improve power factor. And also how is the inrush current limited I know that the as the rotors EMF passes the motor windings a counter EMF is produced decreasing the line current but how is inrush current different in these compared to...
With synchronous motors when loaded current increases just as induction motors. I know this is due to back emf getting smaller as it’s loaded. How is back emf less when loaded? I know it’s something to do with the rotor magnetic flux?
I’m really trying to understand the concepts for AC induction motors but still struggling with how back EMF is produced. This is what I’ve got so far:
As the voltage is applied to the motor windings of an Induction motor the windings create a rotating magnetic field this magnetic field cuts...
Right I have another question. I have a case where there are two separate pump panels both individually isolated. What I want to do is run both pump control (start signal 110vac) into an outside enclosure and then use this signal to create a start stop and e stop circuit. Is it a problem running...
Hi I’ve got the concept of Back emf and with a stalled motor not having any back emf to oppose the current the current drawn will remain high through the motor windings. But I’m trying to get my head around if we then have a high resistance for example on a contactor would this then increase the...
How out of balanced can a motor be I tested a brand new motor which read I 34.4ohms on two of the windings and 38ohms on the third. This was installed by someone else that didn’t check the motor. The motor is not tripping the overload but how bad is this?
I have a question on inductors I’m trying to get my head round. I have a rough understanding how they work as the current through the coil produces a magnetic field and it’s the back EMF that limits the current through the inductor. I also understand with motors when you get a locked rotor the...
