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SSC42-275 Owners Manual
Page
3 of 6 Document: OM-85 Version Code: F
Date: October 30, 2008 Date: May 24, 2023
Electrical System Solutions
3. System Operation
3.1 Electronic Power Switch
The SSC42-275 module power disconnect switch is 100% electronic. When activated, it connects the LOAD
terminal to the +BATTERY terminal, delivering power to the module’s 12 Vdc loads. The highly efcient power
switch has a very low on-resistance, resulting in a very low voltage drop and low internal heat dissipation. As
many DC loads are inductive, the power switch contains an internal clamping diode between its LOAD terminal
and ground. This suppresses negative inductive voltage spikes when the power is switched off. Note that it is
very important that the unit is properly grounded to allow this clamping diode to work effectively.
The power switch monitors the amount of current passing through it, and if this current exceeds specications,
the power switch turns off and stays latched until reset. The current trip point activates if the 275 amp limit is
exceeded for 750 milliseconds. To recover from the latched shutdown condition, the overload condition must be
cleared. Then, either remove battery power from +BATTERY terminal or cycle Input A, B or C to On then Off.
3.2 Control Inputs
The module has ve inputs that perform various functions.
Input A: Activates with +12 volts. Activating this input turns the power switch on. Removing the input turns the
power switch off with no time delay.
Input B: Activates with +12 volts. Activating this input turns the power switch on. Removing this input, a timer
starts. When the timer expires, the power switch shuts off. The timer is adjustable by a single turn potentiometer
located on top of the module. This timer ranges from 0 to 20 minutes on the standard model.
Input C: Activates with ground. Function is otherwise identical to Input B.
Input D: Activated by momentary ground. When activated, the power switch turns on for a xed period of time in
multiples of ve minutes. The interval is determined by how many input pulses are received (one, two or three).
If one pulse is received, the power switch turns on for ve minutes. If two, ten minutes. If three, fteen minutes.
When the period is up or if a fourth pulse is received, the switch turns off.
Input E: Activates by momentary ground. When activated, any timer running is immediately cancelled and reset,
and the power switch turns off.
LED Status Indicator: the amber LED indicator is located on top of the module. Steady on indicates the power
switch is on with no timer running. The LED ashes slowly when a timer is running. It blinks rapidly when a fault
has occurred.
Fault Shutdowns: the following conditions will cause the power switch to shut off and stay latched in the shut off
state until it is reset:
1. over current
2. loss of ground
Resetting Fault Shutdowns: To reset after a fault shutdown, rst remove the source of the fault. Then, do one of
the following:
Disconnect and reconnect the battery cable from the +BATTERY terminal
Or cycle Input A, B or C to on then off.
