ABB Automation Inc.
Substation Automation and Protection Division
Coral Springs, FL 33065
Instruction Leaflet
All possible contingencies which may arise during installation, operation or maintenance, and all details and
variations of this equipment do not purport to be covered by these instructions. If further information is
desired by purchaser regarding this particular installation, operation or maintenance of this equipment, the
local ABB Power T&D Company Inc. representative should be contacted.
Printed in U.S.A
.
ABB
ABB
ABB
ABB
41-223N
CAUTION
!
Before putting protective relays into service,
remove all blocking inserted for the purpose of
securing the parts during shipment. Make sure
that all moving parts operate freely. Inspect the
contacts to see that they are clean and close
properly, and operate the relay to check the set-
tings and electrical connections.
1.0 APPLICATIONS
The type CVQ relay provides instantaneous and time
delay detection of negative sequence overvoltage as
well as responding with time delay to phase-to-phase
undervoltage.
Used in motor protection, the relay protects against
system undervoltage, single phasing of the supply
and reversal of phase rotation of the supply.
The volt-time characteristic of the relay is that of the
CV-7 relay, and the negative sequence overvoltage
pickup is adjustable from 5 to 10 percent of rated
line
to neutral
voltage.
When one of the three supply circuits to a motor is
opened, a negative sequence voltage will appear on
the motor side of the open which is approximately
equal to I
L
/I
S
in per unit where I
L
is positive sequence
current flowing prior to opening the phase and I
S
is
the motor starting current. For most induction motors
this will produce approximately 6% negative
sequence voltage even if single phasing occurs at no
load because of the effect of the magnetizing require-
ment of the motor.
If static (i.e., non motor) load is single-phased with a
motor or group of motors, the negative sequence volt-
age will be greater than the value calculated above.
Single phasing of a predominately static load pro-
duces 50% negative sequence voltage on the load
side of the open circuit.
When the relay is used for overvoltage protection the
back contacts are made at normal voltage and the
negative sequence element is committed to an
instantaneous function. The normally open E2 con-
tact may be used for alarm purposes.
2.0 CONSTRUCTION & OPERATION
The type CVQ relay consists of a polar unit (E) oper-
ating on negative sequence quantities, a negative
sequence voltage filter, full wave bridge, a time
undervoltage relay (CV), an indicating contactor
switch (ICS) and a telephone relay when used. The
principal component parts of the relay and their loca-
tion are shown in Figure 1 (page 2).
2.1
POLAR UNIT
The polar unit consists of a rectangular shaped mag-
netic frame, an electromagnet, a permanent magnet,
and an armature. The poles of the crescent shaped
permanent magnet bridge the magnetic frame. The
magnetic frame consists of three pieces joined in the
rear with two brass rods and silver solder. These non-
magnetic joints represent air gaps, which are bridged
by two adjustable magnetic shunts. The winding or
windings are wound around a magnetic core. The
armature is fastened to this core and is free to move
in the front air gap. The moving contact is connected
to the free end of a leaf spring, which in turn, is fas-
tened to the armature.
Type CVQ Relay
Effective:
October 1999
Supersedes I.L. 41-223L, dated January 1996
( ) Denotes Change Since Previous Issue
