Yaskawa Z1000U HVAC Matrix Bypass - Manual (Page 65)

Use an optional soft starter on the line side of the bypass contactor to limit the current on the bypass circuit to motor FLA or
less. In this case, the bypass contactor is tested for a short-circuit combination rating of 65 kA or greater with the soft starter
and large enough to handle the motor FLA current.
n Overload Relay
The adjustable thermal overload relay (OLR) provides overload protection for the motor in Drive and Bypass operating modes.
The bypass three-phase output power connection to the motor is made to the output terminals of the OLR. The OLR is set up
in the factory to be a manual reset device, requiring operator attention if an overload trip-out is experienced.
n Control Power Transformer
A Control Power Transformer (CPT) is provided to power the bypass 120 Vac control circuit. The VA capacity is determined
by the control circuit and optional functions specified for the unit. The CPT primary is fused in both legs, the secondary is
fused when required by NEC (transformer VA and wire size dependent). One side of the transformer secondary is grounded
to the bypass enclosure.
n Electronic Bypass Control Logic
Operating elements such as indicating LEDs, selector buttons, and control logic are incorporated into a PCB assembly to
eliminate the potential for loose wires after shipment.
The operating elements are located on PCB A3 and the control logic PCB A2 contains the control circuit field wiring terminal
blocks TB1 through TB5.
n Drive/Bypass Logic Interlocks
The bypass 120 Vac logic circuit is interconnected with the drive multi-function digital input terminals and multi-function
digital output terminals to allow a single customer interface to control both drive and bypass circuits. These drive terminals
are not available for field connections. All field control connections are landed at terminal blocks TB1 through TB5 on control
logic PCB A2 and drive PCB A1.
1.5 Bypass Component Descriptions
YASKAWA SIEP YAIZ1D 01A Z1000U HVAC MATRIX Drive Bypass Technical Manual 65
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Receiving