[SBE] Phasor current draw
Edwin Bukont
ebukont at msn.com
Mon Jul 13 17:18:28 EDT 2009
Cris
the bizzareness is that the Tx and DA modes are controlled by momentary closures,,,but the DA/NDA is a rotary 4P latching switch. Thus I figure I need a latching relay that can handle the total current rather than a simple actuator paralleled.
The fun of old plants and no plans.
Edwin Bukont CSRE, DRB, CBNT
V- 240.417.2475; F- 240.368.1265
From: crisa at crawfordbroadcasting.com
To: sbe at sbe.org
Date: Mon, 13 Jul 2009 14:29:39 -0600
Subject: Re: [SBE] Phasor current draw
Edwin:
If those are the solenoid-type RF contactors, at 250 volts you can expect about 6-7A current draw per switch nominal, but the inrush current may be considerably more. So with five towers, it seems that a 30A relay would be boderline.
You should be able to jeep some 24V relays in there to control the phasor remotely. Just hang the NO contacts of a 24V-coil relay across the actuator lines for each mode.
______________________________
Cris Alexander, CPBE, AMD, DRB
Crawford Broadcasting Company
Denver, Colorado
(303) 433-0104
(303) 433-0905 Fax
Assoc. Member AFCCE
From: sbe-bounces at sbe.org [mailto:sbe-bounces at sbe.org] On Behalf Of Edwin Bukont
Sent: Monday, July 13, 2009 2:06 PM
To: sbe
Subject: [SBE] Phasor current draw
I am trying to create a DA/NDA remote control for a 3-tower phasor system. The system has remote for choosing transmitters and Day or Nite. It does not have remote for choosing DA/NDA.
Currently, someone has brought out the Tx and D/N to 240VAC relays with 30A contacts. Is this really necessary?
The mode change itself appears to throw maybe 5 contactors including the towers. I realize that in the DA mode it has to support the current involved with switching of Day and Night.
I want to do my additional control with a 24VDC coil and contacts rated at 15A/250VAC.
Am I missing something here. Do I really need those big power relays or will something smaller suffice. I do not know what the current draw is,,and it would be difficult to amp clamp.
Anybody have any ideas what a 30-40 year old three tower, 3 modes Phasor array might draw in Amps at 250VAC during switching?
Thanks
Edwin Bukont CSRE, DRB, CBNT
V- 240.417.2475; F- 240.368.1265
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