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Keyboard Thug
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Discussion Starter · #1 ·
This thread is not an argument for or against dual IPR's. There are other threads for that.

Like this one,

And this one,
any one still use the terminator twins ? - PowerStrokeNation

This is a discussion of how and why dual IPR's are wired. Please limit comments to the technical aspect using circuit analysis.

JMS1, lets make this a new page in the lab book. I look forward to your input. I'm going to bow out for a bit and let this one ride as it may take a bit of reading and time to post in order to unravel some of the discussion and post a quality rebuttal and/or analysis.

For all concerned this is a good illustration of wiring the IPR's in series. Sustitute 12v for the 16ohms (source voltage) and 6v for the 8ohms at each speaker (voltage drop at each IPR)

Pretend the speakers in this picture are IPRs:

This was my recent response in another thread.

As far as wiring the IPR's in series goes, if you read the thread I linked earlier, it was discussed in depth with the reasons stated. Based on what I know, the reasoning is sound and I made a couple posts as to why I agreed. Feel free to check my work (this is not sarcasm, I would genuinely like to know if the reasoning is sound or not, however it has worked in practice so...). As you are well aware, the IPR's are electromagnetic coils. In a circuit they are calculated the same as resistance ( R equivalent), therefore subject to Ohms Law. In series they will drop the same voltage since the sum of the voltage drops must equal the source, so each will have 6v dropped across them ( I'm sure there is a +/- tolerance but it's probably not relevant). This will effectively halve the work load on each coil, allowing each IPR to equally share the load, prevent the IPR's from causing large pressure variations as Wacker alluded to earlier, and reduce the velocity and heat through the orifice. Rest assured there will be data logging with single, and dual, IPR's when this is installed.
Here are some posts with some in depth circuit comments. Some of them, including some of my own, I think are wrong. JMS1, here is where you come in as I've no doubt you can easily spot the problems. In spite of the errors, I still believe series to be the proper way to wire the IPR's.

-With the IPR coils wired in series, the total resistance of the circuit has roughly doubled. This cuts the current requirements in half.
-If you wire the IPR coils in parallel, the effective resistance of the circuit is now half of what it was. This doubles the current requirement.
-It would not suprise me at all if Ford put a current limiting function in the driver circuitry that shuts off the driver if the current is over a certain threshold. We do that all the time at work: Sometimes with small current sense resistors and A/D converters, sometimes with 'intelligent' drivers.

Now the fun part, if you like the details, is that the magnetic field that opens/closes the IPR valve is driven strictly by current. So, the greater the current through the coil, the stronger the magnetic field, and the more open the valve will be.
By wiring the coils in series, the current in the coils will be halved (for a constant PWM value), cutting the magnetic field in half, according to Ampère's law. So in theory each valve should only be open about half as much as it was as a single IPR. But, that neglects to take into account the return spring, force of oil against the valve, and friction. In the end, I believe the PWM% with a dual IPR system should be slightly more than half the value it was with the single IPR, no other changes to the truck.
Only thing missing is the fact that the coils are inductors, not simple resistors. Depending on the ratio of resistance to inductance the additional resistance by wiring them in series might have little actual effect on the current if the inductive reactance at the 440hz frequency was the largest determinant of the coil's effective resistance.

Now what I don't know is the effect to inductive reactance of running inductors in series with one another.
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This below is definitely correct. (It's HRT not me)

if you have a 12 volt DC circuit and have two resistors of equal value in series there will be a 6 volt drop across each resistor..
This one is mine, I'm fairly certain it's correct.
Although the inductors are not resistors, the values are calculated the same in a circuit, substituting L for R, so in series its the sum and in parallel its the reciprocal of the reciprocal. Calculating the value of L is where it gets tricky and even more so when the signal to the coil is being varied. I'd be more interested in the bleed over effect and proximity.

JMS1, this one is mine. Feel free to tear it apart.
inductance in parallel is calculated the same as resistance in parralel and in fact circuit analysis uses the R equivalent when dealing with inductance (L), and two R/L in parallel would be L=(L1xL2)/(L1+L2), if inductance was 40mH, then L= (40x40)/(40+40)=1600/80=20mH.

I havent taken the time to analyze how much that might affect the rest of your theorizing below, if any, but thought you might like to consider that in any event.

Also the IPR coils are going to be affected much more by Faradays Law than Amperes, since Amperes Law is more concerned with the field created around a conductor carrying current, and not a coil which induces a voltage in opposition to the change in current.

Doubling the inductance /resistance does not necessarily halve the reaction of the coil or the value of the current. Particularly since in a series circuit current remains the same.
Also, when posting in this thread, keep this in mind. LOLLOLLOL


Village Idiot
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how was the old stealth wired
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