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3.5.18 CIRCUIT BREAKER LIMITING STATUS (SSR ONLY)
Purpose: If a control module is not configured as an ATC SLAVE, the circuit breaker limiting
feature is always enabled when using proportional or proportional ambient SSR control modes
with an SSR output switch. This feature is intended to prevent the circuit breaker immediately
upstream of the control module from tripping during a temporary overcurrent condition.
Enabling this alarm will only inform the user that circuit breaker limiting is currently active.
Alarm Mask: ENABLE or DISABLE
Procedure:AdjusttheCIRCUITBREAKERCURRENTRATINGsettingtotheheatingcircuit
breaker size (i.e. 15.0 or 20.0 A). Enable or disable this alarm as required. Note that the
CIRCUITBREAKERLIMITINGALARMdoesnothavetobeenabledinordertoadjustthe
CIRCUITBREAKERCURRENTRATINGsetting.
IMPORTANT:
• This is a non-latching alarm.
• This alarm may be considered an advisory alarm. If the measured current exceeds the level
that would cause the upstream circuit breaker to release, the control module will begin to
switch the SSR on and off rapidly to limit the average current to an acceptable level.
3.5.19 POWER LIMITING STATUS (SSR ONLY)
Purpose: If a control module is not configured as an ATC SLAVE, the power limiting feature
is always enabled when using proportional or proportional ambient SSR control modes with
an SSR output switch. This feature is intended to limit the average amount of power that is
applied to the heating circuit. The control module measures the voltage and current of the
heating circuit and will vary its output switch to limit the amount of power applied to the
heating circuit to the value set by the MAXIMUM POWER setting. Enabling this alarm will only
inform the user that power limiting is currently active.
Alarm Mask: ENABLE or DISABLE
Procedure: Adjust the MAXIMUM POWER setting to the desired value. Enable or disable the
alarm as required. Note that the POWER LIMITING ALARM does not have to be enabled in
order to adjust the MAXIMUM POWER setting.
IMPORTANT:
• This is a non-latching alarm.
• This alarm may be considered more appropriately an advisory alarm and is normally
disabled. It will be active if the MAXIMUM POWER setting is set below the power output
level required for temperature maintenance. In other words, if the heating circuit demands
the maximum power allowed and the alarm is enabled, then this alarm will be indicated
and the output switch will pulse on and off to limit the average power output to a value
approximately equal to the MAXIMUM POWER setting.
3.5.20 SWITCH LIMITING STATUS (SSR ONLY)
Purpose: If a control module is not configured as an ATC SLAVE, the switch limiting feature
is always enabled when using proportional or proportional ambient SSR control modes with
an SSR output switch. This feature is intended to provide protection for the output switch.
Enabling this alarm will only inform the user that switch limiting is currently active and an
excessively high current condition is present. The control module pulses its output switch for
a small number of cycles and reads the resulting current. If the measured current exceeds
the SWITCH RATING setting, then the duty-cycle of its output switch will be varied so that an
average current not exceeding the SWITCH RATING setting is maintained.
Alarm Mask: ENABLE or DISABLE
Procedure: Adjust the SWITCH CURRENT RATING setting to the actual current rating of the
SSR. Enable or disable the alarm as required. Note that the SWITCH LIMITING ALARM does not
have to be enabled in order to adjust the SWITCH CURRENT RATNG setting.
IMPORTANT:
• This is a non-latching alarm.
• This alarm should normally be left enabled. Currents in this range cannot be considered
normal and should be investigated.
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