Watlow SDA Card Shorted Solid State Relay Detector - Manual

There is concern that if a solid state relay fails, it will
most likely fail in a shorted condition. To alleviate this
concern, Watlow Controls has designed a low-cost card
(Watlow P/N 08-5386) that provides a shorted SSR
alarm. It is designed to be used with DC input SSRs,
rated 10 to 40 Amps on either a single phase or two-leg,
three-phase system. In addition to the SDA card, we
strongly recommend semiconductor fuses to protect the
SSR, and a high limit cutout to protect the thermal
system from any runaway conditions. The SDA card mounts directly on the solid state relay
and takes its power from the current flowing through the
current transformer. If there is no input command signal
from the temperature control to the SSR, and there is
current flow to the load, the alarm becomes energized.
The alarm circuit’s output is a triac rated for 300mA @
120 or 240V~ (ac). This can be wired through a
customer supplied latching relay and alarm to 120 or
240 volts.
Watlow Controls
1241 Bundy Blvd., P.O. Box 5580
Winona, MN 55987-5580
Phone: 507-454-5300, Fax: 507-452-4507
SDA Card
Shorted Solid State Relay Detector
Data Sheet
0600-0028-0004 Rev C (1278) Made in the U.S.A.
January, 1998 Printed on Recycled Paper
10% Postconsumer Waste
Figure 1 - SDA Card Dimensions (08-5386)
NOTE: Mount with two 6-32 screws 5/8”
long. (Included with the SDA card.)