ABB HCB-1, Instruction Leaflet

41-971.3M

Type HCB-1 Pilot Wire Relay System

6

sequence current entirely, and operate the relay on
negative-plus-zero sequence current. Tap A is avail-
able to operate in this manner. The relay picks up at
about tap value for all phase-to-phase faults, but is
unaffected by balanced load current or three-phase
faults.

For ground faults, separate taps G and H are avail-
able for adjustment of the ground fault sensitivity to
about 1/4 or 1/8 of the upper tap plate setting. For
example, if the upper tap plate is set at tap 4, the
relay pick-up current for ground faults can be either 1
or 1/2 ampere. It is possible to eliminate response to
zero sequence current. Tap F provides such an oper-
ation.

The response of the relay to various types of faults
are summarized in the following tables.

The voltage, V

F

, impressed by the filter upon the sat-

urating transformer is:

Equ. (1)

Table 3 shows the values of the C-constants in Eq. (1).

For tap settings of C and H, the voltage, V

F

,

impressed by the filter upon the saturating trans-
former is:

Equ. (2)

4.1.

SINGLE RELAY PICKUP (Pilot-wire Open) I

S

Single relay pickup, I

S

, is defined as the phase cur-

rent required to operate one relay with the pilot-wire
side of the insulating transformer open circuited (H1-
H4). The single relay pickup point in terms of filter
voltage is:

Equ. (3)

where T is the saturating transformer tap value. Sin-
gle relay pickup is defined by equating (2) and (3):

Equ. (4)

Current I

S

 varies with the type of fault. For example,

for a 3 phase fault, I

S

 = I

A1

, since only positive

sequence current is present. Substituting I

S

 = I

A1

 in

Equ. (4) and rearranging, the 3 phase fault pickup is:

Equ. (5)

For 4 Tap:

For a phase A to ground fault, if I

A1

 = I

A2

 = I

A0

Table 1 

Phase Faults

Sequence Components

in Sequence
Filter Output

Taps

Pickup –

Multiples of T

3Ø

AB
CA

BC

Pos., Neg., Zero

C

1

.86

.53

Pos., Neg., Zero

B

2

.9

.66

Neg., Zero

A

—

1.0

0

1.0

0

Table 2 

Ground Faults

Com
b.

Lower Left 

Tap

Ground Fault Pickup

Multiples of T

Tap

Tap G

Tap H

1

C

.25

.12

2

B

.20

.10

3

A

.20

.10

V

F

C

1

I

A

1

C

2

I

A

2

C

0

I

0

+

+

=

Table 3 

Constants For Equation (1)

Tap

C

1

C

2

C

0

A

0

0.26

—

B

-0.08

0.34

—

C

-0.20

0.46

—

F

—

—

0

G

—

—

2.5

H

—

—

4.9

V

F

.2

I

A

1

–

.46

I

A

2

4.9

I

A

0

  Volts

+

+

=

V

F

0.2

T Tap

C

(

)

V

F

0.15

T Tap

A

(

)

=

=

V

F

0.16T (Tap B)

=

0.2

T

0.2

I

A

1

–

.46

I

A

2

4.9 

I

A

0

+

+

=

I

S

I

A

1

0.2

T

.2

-----------

+

T

    (3 phase fault)

=

=

I

S

T

4 amp       (3 phase fault)

=

=