InteliATS
NT
PWR, SW version 2.5, ©ComAp
– May 2015
58
IA-NT- PWR-2.5-Reference Guide.pdf
H
INT
:
This transition can perform fastest possible changeover if
Transfer Del
is set to zero value.
Overall blackout time then equals to 20 ms + breaker reaction time.
H
INT
:
Use longer delay time to avoid problems with motor starters. (Motor starts prefer to see break of a
few seconds so they can initialize properly).
H
INT
:
To avoid issues with contactor mechanical interlocks use delay 0.75s or longer (mech. interlock on
contactors takes some time to clear). If you try to close one contactor before interlock has cleared
it can jam and you end up without supply to load).
2. Open In-phase Transition
Open In-phase Transition represents special kind of Open Delayed Transition where delay during
changeover is reduced to minimal possible value and transition initiates only when both power
sources are in sync.
Transfer Del
setpoint value is ignored (equals to zero). See description of
passive synchronization for more info.
This kind of transition is suitable for such systems where fast changeover (very short blackout) is
required, huge inductive load (e.g. large electric motor) is involved and it is not possible to use
Closed Transition due to some reason.
Two or three position ATS switch or two independent breakers/contactors can be used as
switching element. Reaction time of whole switching mechanism (including control relays) affects
overall changeover time and in-phase transfer accuracy.
