[RE-wrenches] DC Solenoid Coil Current

[Larry Crutcher, Starlight Solar Power Systems]

Pure genius, Dan. Exactly what I needed. You are truly an asset to the Wrench board.

Thanks Frank for the tip on the MOSFET. Good to hear from you.

Thank you,

Larry Crutcher




On Feb 11, 2014, at 6:16 PM, Exeltech <exeltech at yahoo.com> wrote:

Larry,

A latching relay isn't suitable for fail-safe applications.

Look into the "Kilovac Czonka III EV200HAANA".  This series has a coil "economizer" that reduces coil current (and thus power consumption) after pull-in.  Rated coil power is less than 2 watts.  Models are good to 900Vdc and up to 500A.

Coil inrush current on one model I found is spec'd at 3.8 A for a 130 milliseconds, so you'd need an external transistor to drive it from the computer.  If power consumption is a critical aspect, use a suitable MOSFET.  If you don't mind wasting another watt or two, a bipolar NPN will also work.  The coil current throttles back to less than 100 mA at 12Vdc after contact closure.  Because a specialized electronic power supply is driving the coil, Kilovac rates the DC input to the coil driver at anything from 9Vdc to 36Vdc.

Here's the Allied page: http://www.alliedelec.com/search/productdetail.aspx?SKU=70062411

Not cheap .. but excellent quality.  If you're a registered reseller with Allied, the $ is less.


Dan

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On Tue, 2/11/14, Larry Crutcher, Starlight Solar Power Systems <larry at starlightsolar.com> wrote:

Subject: [RE-wrenches] DC Solenoid Coil Current
To: "RE-wrenches" <re-wrenches at lists.re-wrenches.org>
Date: Tuesday, February 11, 2014, 6:43 PM

Hello Wrenches,

We're preparing to offer Lithium batteries to some of our customers as a replacement to lead acid in recreational vehicles. RV batteries can have multiple charge sources simultaneously so I have worked out protective circuitry to interface with a EMS computer. To insure failsafe operation, I need to install 2 solenoids that will be active 24/7, opening only when fault conditions are met.

The solenoids I have looked at (200 amp) have a coil current of about 1 ampere each which equates to 600Wh daily consumption. I'de like to reduce that BUT the computer only provides a +12v or 0 volt state. 

 *  Does anyone know of a latching solenoid that will work with a 12v hi/lo voltage state,
 *  OR an interface or circuit for hi/lo to control latching relay
 *  OR a solenoid with a very low quiescent current when on? 

Many thanks in advance, 

Larry Crutcher


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