A review of the Newark and Electrosonic catalogs reveals a smorgasboard of
solid state relays. For simple power-on/power-off there are plenty of
choices that will easily handle the up to 20-25 amps of operating current
you're looking for (at 240 V), and will handle several hundred amps of
single cycle surge current (during start-up for example). Further, many of
these are "zero-crossing start and stop", which means that they don't
activate until the line voltage crosses through "zero" volts. This is a
mini soft start because it prevents random connection to the mains when the
voltage could be at it's peak value. A wide variety of control voltages
are available - both AC and DC.
For soft start, you would add a second solid state timed relay, such as the
Crydom DSD/DLD series, to short out the line surge resistors. Time delay
is adjustable by placing different value of resistors across the time deley
control pins. Typical time delays for this particular product range from
0.1 sec to 133 sec.
Crydom also makes solid state "soft start" modules (series "SST") but there
isn't much information about how they function.
I can't see any reason not to use solid state relays. Some of the
commercial amps MUST be using these somewhere - they're small, quiet, no
moving parts or contacts.
Phil
At 02:36 PM 3/21/99 -0600, you wrote:
>
>They are OK for power on, but will not work for soft-start.
>They are too fast to let the HV build up to 2/3 of max.
>and cannot be slowed down like a mechanical relay.
>GL!
>Phil, K5PC
>
>-----Original Message-----
>From: Arthur Moe <kb7ww@chatusa.com>
>To: Amps <amps@contesting.com>
To: <amps@contesting.com>
>Date: Sunday, March 21, 1999 12:35 PM
>Subject: [AMPS] Info needed: Soild Statte Relays
>
>
>>
>>Are Solid State Relays suitable for main power on and soft start in
>>a QRO Amp?
>>
>>Art
>>KB7WW
>>
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>>
>>
>
>
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>
>
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