Buck n Boost Rectifier?

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rruiz642

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Hello all,

Apparently I slept through a part of electrical theory on this one, but hopefully I can get some assistance.

I currently overseas working with 240/415 50hz power. I'm installing a simple 240 to 24VAC transformer for a door latching mechanism. Because I later found out it works on 24DC, I purchased some Folger Adam 12/24VAC to 12/24VDC 2-wire rectifiers.

A simple installation, except for the fact that I smoked my magnetic door release's circuit board. Apparently, I getting 242VAC before the transformer, 25VAC after the transformer, 25VAC into the rectifier and 35VDC after the rectifier into the door latching mechanism.

Is it then reasonable to assume that the 50hz frequency is affecting the rectifier to produce +10VDC. I wasn't aware that rectifiers are frequency dependent. Is there a formula for determining voltage loss/increase when using a 60hz device in a 50hz system or vice versa? Of course, I normally don't use equipment like this becuase of possible higher internal amperage in motor winderings and such.

thanks for any suggestions,

Richard
 
I don't see how the 50 hertz would increase the output, as the rectifier would just be putting out a slower rate of pulsating dc, of course i'm not an engineer, so I could be wrong. Maybe one of the diodes are blown not giving you full wave rectification.
 
080522-0659 EST

Richard:

If by 2 wire you mean a object with only 2 wires, then you have a single diode as distinguished from a 4 wire device that might enclose a group of 4 diodes in a bridge circuit.

A single ideal diode will will pass current with zero reistance in one direction and look like an infinite resistance in the other direction. The two ends of a diode are called cathode and anode which derive from the vacuum tube days. The cathode end is usually identified by a dark bar. A positive voltage applied to the anode relative the cathode is the forward biased direction and causes current to flow.

In a semiconductor diode in the forward biased direction there is a voltage drop of around 1 V, but it does change with current. Before burnout somewhat over 1 V typically.

If you have a 24 V RMS sine wave source with a diode and resistor as the load, then the average DC output voltage is about 24 * 0.636 / 2 and minus about the 1 V drop of the diode. This is a half wave rectifier with a resistive load. Change to a full wave bridge and the 0.636/2 becomes 0.636 and the 1 V diode drop becomes 2 V.

Next with either the half wave or full wave rectifier if you add an adequately large capacitor across the resistor, then the voltage will be the peak of the AC input minus the diode(s) drop. Or in this example 24 * 1.414 = 34 V minus the diode drop.

Your circuit board probably had a filter capacitor at the input that producing a DC voltage approximately the peak of your AC voltage.

.
 
if the thing has a circuit board in it, vs it just being a solenoid or whatever, it probably needs a 24vdc regulated power supply, not a xfmr + rectifier.
 
rruiz642 said:
Hello all,

Apparently I slept through a part of electrical theory on this one, but hopefully I can get some assistance.

I currently overseas working with 240/415 50hz power. I'm installing a simple 240 to 24VAC transformer for a door latching mechanism. Because I later found out it works on 24DC, I purchased some Folger Adam 12/24VAC to 12/24VDC 2-wire rectifiers.

A simple installation, except for the fact that I smoked my magnetic door release's circuit board. Apparently, I getting 242VAC before the transformer, 25VAC after the transformer, 25VAC into the rectifier and 35VDC after the rectifier into the door latching mechanism.

Is it then reasonable to assume that the 50hz frequency is affecting the rectifier to produce +10VDC. I wasn't aware that rectifiers are frequency dependent. Is there a formula for determining voltage loss/increase when using a 60hz device in a 50hz system or vice versa? Of course, I normally don't use equipment like this becuase of possible higher internal amperage in motor winderings and such.

thanks for any suggestions,
Richard
Click to expand...

Lets forget about the volts, amps, diodes, hertzes, and phases of the moon. Something else is wrong in your senario. You ain't telling us everything. How about a part number or two?

Folger Adams door controls are the best. They have been making electric door controls since 1880. According to their latest catalog, they offer two flavors, 12VDC@.51 amps and 24VDC@.25 amps, period.

Their door solinoids work on a momentary voltage pulse. I really do not think it much matters what the range of voltage is, 12, 24, 36 VDC, the applied voltage is only momentary, and just about any momentary DC pulse will operate the release mechanism.

I am years retired from the trade here, may be speaking out of my hat, but I think not . . .

Have you called Folger Adams tech support (800-461-3007)? They are very helpfull.

How about some feedback from you?

Best Wishes Everyone
 
Gar's explanation is exactly correct. Note it was the board that was smoked, not the solenoid.

In Europe, door solenoids are normally power on to lock, so that you can comply with the requirement to have an emergency exit button (normally a break glass thing) which simply interrupts supply to the solenoid, and it falls open.

If you are using something unusual (for Europe!), you need to ensure that you can comply with the building code egress requrements.
 
You ain't telling us everything. How about a part number or two?

I'm going to agree with Steve here. My experience is that these things are not that fussy. What door release are you using that has a circuit board? I want to look it up for myself.

-Hal
 
Rectifier

Rectifier

Thanks for all the great info. We cut into one of the rectifiers and its built around a 35V capacitor. My Fire Alarm techs were attempting to call Folger Adams to get more info.

I'm still waiting on feedback from that conversation. I do appreciate the education.
 
rruiz642 said:
Thanks for all the great info. We cut into one of the rectifiers and its built around a 35V capacitor. My Fire Alarm techs were attempting to call Folger Adams to get more info.

I'm still waiting on feedback from that conversation. I do appreciate the education.
Click to expand...

And thank you for the feedback. How about a part number or two? I still would like to follow up if only for my edification and enjoyment. Circuit board in a Folger Adams?

Best Wishes Everyone
 
Folger Adams

Folger Adams

Here is the part number for the rectifer: 076-0712-011. I purchased it from Grainger (3ZV22) and matched it with a White-Rodgers 24V output transformer p/n 90-T60C3 (Grainger # 6WU94).

Incoming power is 242v, phase-to-ground, 50hz.

Thanks
 
rruiz642 said:
Here is the part number for the rectifer: 076-0712-011. I purchased it from Grainger (3ZV22) and matched it with a White-Rodgers 24V output transformer p/n 90-T60C3 (Grainger # 6WU94).

Incoming power is 242v, phase-to-ground, 50hz.

Thanks
Click to expand...

Thank you again. I was looking for a Folger Adams door strike part number, so I can look it up. Just do not understand the need the need for a circuit board in a door strike. Of course we have microprocessors in our kitchen toasters now-a-dayz.

Going out on a limb here, almost any diode rated at about one amp and a PIV of 200 volts should be adequate for your need. Cost about $.25 USD.

Don't give up on me, still interested.

Best Wishes Everyone
 
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