SERIES AP445 ACROPACK
USER
’S MANUAL
Acromag, Inc. Tel: 248-295-0310
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www.acromag.com
2 and Figure 3 in Appendix A).
The SSR’s employed are rated for a much higher voltage than specified for
the AP445. However, the printed circuit board foil spacings limit applied
voltages to ±60VDC or AC peak. Each port (group of eight channels) has a
single common. Due to the printed circuit board foil width, each port is
limited to 1A maximum. Thus the sum of currents conducted by the eight
channels must stay below that maximum. The low on resistance of the SSR’s
helps to reduce their power dissipation when they conduct high currents;
however, given the large number of channels on the board, adequate air
circulation must be maintained. The SSR’s do not contain any built in current
limiting for their protection. Please refer to the Specifications in Chapter 6.5
for providing external current limiting, if necessary. The SSR’s provide clean,
bounce free switching and can replace electromechanical relays in many
applications. SSR switching speeds are comparable to electromechanical
relays (1ms typical) but are slow compared to high speed optocouplers.
Output operation is “Fail-safe.” That is, the outputs are always OFF upon
power-up reset, and are automatically cleared following a software (reset
register) or system software reset. This is done for safety reasons to ensure
reliable control of the output state under all conditions.
