[SBE] Phasor current draw..clarify

[Edwin Bukont]

and before i get a barrage of WTF emails,,,I am talking about using parallel motor starting contactors or maybe even an ATS as a big relay.  i was not talking about using RF contactors to control the phasor.


Edwin Bukont CSRE, DRB, CBNT 
V- 240.417.2475; F- 240.368.1265 

 




 


From: crisa at crawfordbroadcasting.com
To: sbe at sbe.org
Date: Tue, 14 Jul 2009 06:50:20 -0600
Subject: Re: [SBE] Phasor current draw




I can't imagine why you would need a latching switch. The reality is that would necessarily rely on the end-of-travel NC microswitch on the RF contactor itself to open the circuit to the solenoid when end-of-travel is reached. How many times over the years have I seen solenoids burned out because those microswitch contacts did not open?
 
Love to see a diagram of that thing...
 

______________________________
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 3:18 PM
To: sbe
Subject: Re: [SBE] Phasor current draw


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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