ABB CM Manual

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.
!CAUTION
Before putting relays into service, remove all
blocking which may have been 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 settings and electrical connections.
1.0 APPLICATION
The type CM relay is an induction type relay designed
to protect polyphase electrical machinery against
phase unbalance or phase failure.
As shown in figure 6 the relay may be used with
either three or two-current transformers. With three
ct’s the accuracy class must be at least C50; with two
ct’s the accuracy class must be at least C70. Other-
wise ct errors during motor starting may cause
undesired CM tripping.
2.0 CONSTRUCTION & OPERATION
The type CM relay consists of two main current units
and their associated resistor and an indicating con-
tactor switch (ICS), or an ac indicating contactor
switch (ACS). The principal component parts of the
relay and their location are shown in figures 1 and 2.
2.1. MAIN UNIT
Each main unit has a pair of electromagnets operat-
ing on a single disc. The disc is damped by a perma-
nent magnet. Each disc carries its own set of
contacts with the two sets being connected in paral-
lel, in order that either disc may close the trip circuit.
The electromagnet pair are mounted face to face on
opposite sides of the disc, and so connected that the
electrical torque of one electromagnet opposes that
of the other, thus producing balanced operating
torque on the disc when the magnitudes of the cur-
rents through each of the two electromagnets are
equal. One of the electromagnets on the lower disc is
connected in series with one of the electromagnets
on the upper disc. Thus phase A current may balance
phase B current on the upper disc, and phase B cur-
rent balance C current on the lower disc. Conse-
quently with balanced system conditions, no
operating torque is produced on the two discs, but
with unbalanced conditions or an open phase the bal-
ance on the disc is upset and one or two sets of con-
tacts close.
Each electromagnet has a main coil located on the
center leg of an “E” type laminated structure that pro-
duces a flux which divides and returns through the
outer legs. A shading coil located on one of the outer
legs of the “E” structure causes the flux through that
leg to lag the main pole flux. The out-of-phase fluxes
thus produced in the air gap will cause disc rotation.
A resistor located to the rear of each main unit is
used as an aid in balancing the opposing torques by
controlling the current flow through the shading coils.
For some CM relays, the front electromagnet may
have adjustable plugs which are used to aid in cali-
bration.
41-181.2K
Effective: June 1980
Supersedes I.L. 41-181.2J, dated March 1978
( | ) Denotes Change Since Previous Issue
Type CM Phase
Balance Current Relay

41-181.2K
2
Figure 1a. Non-Tapped Type CM Relay without case
(Front View
Figure 1b. Non-Tapped Type CM Relay without case
(Rear Vies)

3
41-181.2K
Figure 2a. Type CM Tapped Relay without case
(Front View)
Figure 2b. Type CM Tapped Relay without case
(Rear View)

41-181.2K
4
The contacts are single-pole, double throw. The
moving contact is fastened directly to the disc shaft
and the electrical connection is made thru a spiral
spring fastened to the moving contact arm and frame
assembly.
2.2. INDICATING CONTACTOR SWITCH (ICS)
The dc indicating contactor switch is a small clapper
type device. A magnetic armature, to which leaf-
spring mounted contacts are attached, is attracted to
the magnetic core upon energizing of the switch.
When the switch closes, the moving contacts bridge
two stationary contacts, completing the trip circuit.
Also during this operation two fingers on the arma-
ture deflect a spring located on the front of the
switch, allowing the operation indicator target to
drop.
The front spring, in addition to holding the target, pro-
vides restraint for the armature and thus controls the
pickup value of the switch.
2.3. AC INDICATING CONTACTOR SWITCH
(ASC)
The ac indicating contactor switch unit is a small ac
operated clapper type device. A magnetic armature,
to which leaf-spring mounted contacts are attached,
is attracted to the magnetic core upon energization of
the switch. When the switch closes, the moving con-
tacts bridge two stationary contacts completing the
trip circuit. Also, during the operation, two fingers on
the armature deflect a spring located on the front of
the switch which allows the operation indicator target
to drop.
3.0 CHARACTERISTICS
The non-tapped type CM relay has a minimum
pickup current of one ampere and a continuous ther-
mal rating of seven amperes. The tapped CM relay
has a minimum pickup of 1, 2 or 3 amperes, depend-
ing on the tap setting and a continuous of 7 amperes.
The minimum pickup current is defined as the pickup
current of each electromagnet with the other paired
electromagnet de-energized.
The relay may be utilized for continuous load cur-
rents of from one to seven amperes. The characteris-
tic curve of the relay is shown in figure 3.
3.1. TRIP CIRCUIT
The main contacts will safely close 30 amperes at
250 volts dc and the seal-in contacts of the indicating
contactor switch will safely carry this current long
enough to trip a circuit breaker.
The indicating contactor switch (ICS) has two taps
that provide a pickup setting on 0.2 or 2 amperes. To
change taps requires connecting the lead located in
front of the tap block to the desired setting by means
of a screw connection.
For 0.5 ampere ACS, the 1 second coil rating is 18.0
amperes ac. For 1.0 ampere ACS, the 1 second coil
rating is 44.0 amperes ac.
3.2. TRIP CIRCUIT CONSTANTS
Contactor Switch –
ICS
0.2 ampere tap - 6.5 ohms dc resistance
2.0 ampere tap - 0.15 ohms dc resistance
ACS
0.5 ampere ACS - 18 ohms ac impedance
1.0 ampere ACS - 4.5 ohms ac impedance
4.0 ENERGY REQUIREMENTS
The burden of each electromagnet is as follows:
Figure 3. Typical Operating Curve of the Type CM Relay
188A145

5
41-181.2K
This represents the burden on the current trans-
former connected to terminals 4 and 5 or 8 and 9.
The burden on the current transformer connected to
terminals 6 and 7 is twice the stated values.
5.0 SETTINGS
5.1. MAIN UNITS
No setting is required on the non-tapped relay
because it is calibrated for one ampere sensitivity
and is set to operate on an unbalance as shown in
the operating curve of figure 3. For the tapped relay,
select the minimum tap that is compatible with the
current transformer error expected during motor
starting. All taps should be set identically. On the 2
and 3 ampere tap, the relay contact should make
within ±5% of tap value with no current in the other
unit on the same disc.
5.2. INDICATING CONTACTOR SWITCH (ICS)
No setting is required on the ICS unit except the
selection of the 0.2 or 2.0 ampere tap setting. This
selection is made by connecting the lead located in
front of the tap block to the desired setting by means
of the connecting screw.
5.3. AC INDICATING CONTACTOR SWITCH
(ACS)
No setting is required on the ACS unit with the core
screw locked in its “all in”position. The unit should
operate and drop its target at a value not greater than
its rated operating current.
6.0 INSTALLATION
the relays should be mounted on switchboard panels
or their equivalent in a location free from dirt, mois-
ture, excessive vibration and heat. Mount the relay
vertically by means of the rear mounting stud or
studs for the type FT projection case or by means of
the four mounting holes on the flange for the semi-
flush type FT case. Either the stud or the mounting
screws may be utilized for grounding the relay. Exter-
nal toothed washers are provided for use in the loca-
tions shown on the outline and drilling plan to
facilitate making a good electrical connection
between the relay case, its mounting screws or
studs, and the relay panel. Ground wires are affixed
to the mounting screws or studs as required for
poorly grounded or insulating panels. Other electrical
connections may be made directly to the terminals by
means of screws for steel panel mounting or to the
terminal stud furnished with the relay for thick panel
mounting. The terminal stud may be easily removed
or inserted by locking two nuts on the stud and then
turning the proper nut with a wrench.
For more detailed information on the FT case refer to
Instruction Leaflet 41-076.
7.0 ADJUSTMENTS & MAINTENANCE
The proper adjustments to insure correct operation of
this relay have been made at the factory. Upon
receipt of the relay no customer adjustments, other
than those covered under “SETTINGS”should be
required.
7.1. ACCEPTANCE CHECK
The following check is recommended to insure that
the relay is in proper working order.
7.1.1. Main Units
For all electrical checks refer to test diagram figure 4
for tapped CM, put tap screw in one amp setting.
Non-Tapped Relay
Volt
Ampere
Power
Factor
Angle
Current
Amperes Frequency
1
5
1
5
1
5
60
60
50
50
25
25
0.95
15.00
0.85
14.5
0.46
8.00
74
73
72
71
55
54
Tapped Relay
Volt
Ampere
Power
Factor
Angle
Tap Current
Amperes Frequency
1
1
2
2
3
3
1
5
2
5
3
5
60
60
60
60
60
60
0.95
15.00
0.95
5.8
1.05
2.8
74
73
65
65
54
54

41-181.2K
6
1. Contacts
Stationary contacts assembly should be aligned
with respective marks located on scale plate,
prior to checking the relay. These marks indicate
approximately 1 ampere of unbalance.
2. Minimum Trip Current
NOTE: The front electromagnet energized alone
will produce a disc rotation to the left while a rear
electromagnet energized alone will produce a
disc rotation to the right.
Minimum trip can be checked by energizing
either the front or rear electromagnets alone and
noting that the moving contact makes with its
respective stationary contact at one ampere.
3. Balance Check
Apply one ampere through the front and rear
electromagnets simultaneously. The moving
contact should remain substantially midway
between the stationary contacts. A similar check
should be made utilizing six amperes.
4. Time Curve
Contact travel is from balanced position to either
the right or left stationary contacts.
Electromagnets are to be energized alone (zero
restraint). Apply ten amperes and note that con-
tacts make at one second ±10%. Time curve
characteristic per figure 5.
7.1.2.1. Indicating Contactor switch (ICS)
Close the main relay contacts and pass sufficient dc
Figure 4. Typical Time Curve with Zero Restraint of the Type CM Relay
Sub 2
188A146
Figure 5. Diagram of test connection for the non-tapped
Type CM Relay in the FT-31 Case. For tapped
CM place tap screw in 1 amp. tap setting.
Sub 3
188A143

7
41-181.2K
current through the trip circuit to close the contacts of
the ICS. This value of current should be not greater
than the particular ICS tap setting being used. The
operation indicator target should drop freely.
The contact gap should be approximately .047”
between the bridging moving contact and the station-
ary contacts. The bridging moving contact should
touch the stationary contacts simultaneously.
7.1.3.2. AC Indicating Contactor Switch (ACS)
Close the main relay contacts and pass sufficient ac
current through the trip circuit to close the contacts of
the ACS. This value of current should be not greater
than the particular ACS rated operating current being
used. The operation indicator target should drop
freely.
The contact gap should be approximately 3/32”
between the bridging contact and the adjustable sta-
tionary contacts. The bridging moving should touch
both stationary contacts simultaneously.
7.2. ROUTINE MAINTENANCE
All relays should be inspected periodically and the
time of operation should be checked at least once
every year or at such other time intervals as may be
dictated by experience to be suitable to the particular
application. Phantom loads should not be used in
testing induction-type relays because of the resulting
distorted current wave form which produces an error
in timing.
All contacts should be periodically cleaned. A contact
burnisher style #182A836H01 is recommended for
this purpose. The use of abrasive material for clean-
ing contacts is not recommended, because of the
danger of embedding small particles in the face of
the soft silver and thus impairing the contact.
8.0 CALIBRATION
Us the following procedure for calibrating the relay if
the relay has been taken apart for repairs or the
adjustments disturbed. This procedure should not be
used until it is apparent that the relay is not in proper
working order. (See “Acceptance Check”).
8.1. MAIN UNITS
For all electrical checks refer to test diagram figure 5.
For tapped CM, put tap screw in one amp tap setting.
1. Balance Setting
a) Mechanical balance - adjust spiral spring
until moving contact is located substantially
in the center of the scale plate.
b) Electrical Balance
1. Apply two amperes on front and rear
electromagnets and adjust resistor at
rear of specific unit being tested such
that the moving contact is in balance,
i.e., moving contact is aligned per part
“a”above.
2. Apply twenty amperes on front and rear
electromagnets for approximately two
seconds and note that the moving con-
tact does not deviate from the balanced
condition more than approximately 1/4
inch.
For CM relays with adjustable magnetic plugs, only
the right-hand plug may be adjusted. At the factory,
the right-hand plug is adjusted to help obtain a bal-
anced condition of the contact at 20 amperes. The
moving contact is again checked at 2 amperes. Little
adjustment, if any, is expected to be necessary in the
field.
2. Minimum Trip Setting
The front electromagnet energized alone should
produce a disc rotation to the left while the rear
electromagnet energized alone should produce a
disc rotation to the right.
a) Apply one ampere to front electromagnet
and adjust left stationary contact until it just
makes with the moving contact. This setting
should correspond with the marking on scale
plate.
b) Apply one ampere to rear electromagnet and
adjust right stationary contact until it just
makes with the moving contact. This setting
should correspond with marking on scale
plate.
3. Operating Curve
Apply six amperes to front electromagnet and
vary current flowing through rear electromagnet.
a) The moving contact should make with the

41-181.2K
8
right stationary contact between 6.5 and 7.1
amperes.
b) The moving contact should make with the
left stationary contact between 5.5 and 5.0
amperes.
4. Time Curve
NOTE: Contact travel is from balanced position
to either the right or left stationary con-
tacts.
a) Apply 10 amperes to rear electromagnet
(front electromagnet de-energized) and
adjust permanent magnet for an operating
time to right contact of 1.0 ±0.10 seconds.
8.2. INDICATING CONTACTOR SWITCH (ICS)
Close the main relay contacts and pass sufficient dc
current through the trip circuit to close the contacts of
the ICS. This value of current should not be greater
than the particular ICS tap setting being used. The
operation indicator target should drop freely.
8.3. AC INDICATING CONTACTOR SWITCH
(ACS)
Close the main relay contacts and pass sufficient ac
current through the trip circuit to close the contacts of
the ACS. This value of current should not be greater
than the particular ACS rated operating current being
used. The operation indicator target should drop
freely.
9.0 RENEWAL PARTS
Repair work can be done most satisfactorily at the
factory. However, interchangeable parts can be fur-
nished to the customers who are equipped for doing
repair work. When ordering parts, always give the
complete nameplate data.
Figure 6. Relay Type CM Phase Balance Current With Taps And Acs Unit In Type FT-31 Case.
876A588

9
41-181.2K
Figure 7. Internal Schematic of the Non-Tapped Type CM Relay in the Type FT-31 Case
Figure 8. Internal Schematic of the Tapped Type CM Relay in the Type FT-31 Case
187A232
762A812

41-181.2K
10
Figure 9. Element Assembly for CM Relay (Front View)

11
41-181.2K
Figure 10. External Schematic Diagram of the Type CM Relay in the Type FT-31 Case
Sub 4
188A144
Figure 10. External Schematic Diagram of the Type CM Relay in the Type FT-31 Case

Printed in U.S.A.
ABB Automation Inc.
4300 Coral Ridge Drive
Coral Springs Florida 33065
TEL: [phone]
FAX: [phone]
visit our website at www.abbus.com/papd
41-181.2K
Figure 11. External Schematic Diagram of the Type CM Relay in the Type FT-31 Case
57S902