Honeywell Vertex Operating Manual page 54

1. Primary protection only is required if the
transformer is single-phase and the secondary
has only two wires. Overcurrent protection
rating and location are shown below.
2. If the branch circuit feeding the transformer
has overcurrent protection to meet the
individual protection requirements in Example
1, then individual transformer protection is
not required.
Vertex Technical Handbook
V
ertex 72-Point Continuous Monitor
TM
1. Primary and secondary protection is required
if the transformer has more than two wires on
the secondary circuit.
2. If the branch circuit feeding the transformer
has overcurrent protection to meet the
individual primary overcurrent protection
requirements in Example 3, then individual
primary protection is not required. Secondary
OCP is required as shown below.
Supply Voltage
Branch Circuit
feeding
transformer meets
this requirement
2-13
Individual transformer overcurrent
protection NOT REQUIRED
Transformer
Secondary
Overcurrent
Protector
Pri. Sec.
Load