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.
Type CV Frequency
Compensated Voltage Relay
Effective: September 1999
Supersedes I.L. 41-201.2E, Dated September 1990
( | ) Denotes Changes since previous issue
41-201.2G
CONTENTS
This leaflet applies to the following types
of relays:
• CV-21 Long Time Undervoltage Relay
• CV-22 Short Time Undervoltage Relay
• CV-24 Long Time Overvoltage Relay
• CV-25 Short Time Overvoltage Relay
• CV-26 Long Time Over or Undervoltage
Relay
• CV-27 Short Time Over or Undervoltage
Relay
!
CAUTION
Before putting relays into service, remove all
blocking which may have been inserted for the
purpose of securing the parts during ship-
ment, 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 settings and electrical con-
nections.
1.0 APPLICATIONS
The type CV relays are single-phase induction-disc
type relays operating either on under or over voltage
or both. These relays frequency compensated such
that their pickup between 30 and 90 Hz is within 5%
of the value at rated frequency.
2.0 CONSTRUCTION AND OPERATION
The types CV-21, CV-22, CV-24, CV-25, CV-26 and
CV-27 relays consist of a voltage unit, an auxiliary
telephone type relay and an indicating contactor
switch (ICS). The component parts of the relays are
connected as shown in the internal schematic dia-
gram. Some style relays contain an instantaneous
indicating voltage switch (IIV) which also operates
independent of frequency.
2.1
VOLTAGE UNIT (CV)
The overvoltage unit is an “E” type laminated struc-
ture with coils on each leg. The coil on the center leg
of the structure is an autotransformer winding with a
tapped primary. The secondary winding of the
autotransformer is connected to identical coils called
lag coils on the outer legs of the “E” type laminated
structure. The coils are connected in such a manner
that the combination of all fluxes produced result in
out-of-phase fluxes in the air gap. The out-of-phase
air gap fluxes produced cause a contact closing
torque.
The undervoltage unit operates on the same princi-
ples as the overvoltage unit except the connections to
the lag coils are reversed to cause the out-of-phase
fluxes to produce a contact opening torque.
The units are frequently compensated by means of a
resistor in the outer coil circuit.
2.2
INSTANTANEOUS INDICATING VOLTAGE
SWITCH (IIV)
The instantaneous trip unit is a small ac operated clap-
per type device. A magnetic armature, to which
