Multilin PROTECT 4A-120 User manual

MOTOR PROTECTION RELAY
INSTRUCTION MANUAL

INSTRUCTION MANUAL
MOTOR PROTECTION RELAY
PATENTS U.S. 4,241,336 4,224,651
CANADA 1,130,383
COPYRIGHT 1982, 1986, 1988 MULTILIN
ALL RIGHTS RESERVED
215 Anderson Ave., PO Box 2700
Markham, Ontario, Canada L3P 4C7
Tel:[phone] Fax:[phone]

TABLE OF CONTENTS
1. INTRODUCTION
1.1 Motor Protection Requirements................................................... 1
1.2 Protect 4A Features.....................................................................3
1.3 Typical Applications .....................................................................4
1.4 Order Code ..................................................................................5
1.5 Technical Specifications ..............................................................6
2. INSTALLATION
2.1 Physical Dimensions ...................................................................7
2.2 Mounting ......................................................................................9
2.3 External Wiring ..........................................................................10
2.4 Control Power ............................................................................ 11
2.5 Trip Contacts .............................................................................12
2.6 Thermistor Input ........................................................................12
2.7 Programmable Controller Output .............................................. 14
2.8 Tamper Proof Cover ..................................................................14
2.9 Field Options — Auto Reset ....................................................15
Mechanical Jam ............................................16
Ground Fault Indication Only ........................16
Single Phase Defeat .....................................17
Factory Service .............................................17
2.10 Environment ..............................................................................17
3. SETUP AND USE
3.1 Control and Indicators ............................................................... 19
3.2 Full Load Control .......................................................................20
3.3 StallTime Control ......................................................................23
3.4 Ground Fault (Earth Leakage) Level Control ............................ 24
3.5 Ground Fault (Earth Leakage)Time Delay Control...................25
3.6 Single Phase Detection .............................................................26
3.7 ThermistorTrip Detection ..........................................................27
3.8 Reset/Test Button ......................................................................28
3.9 MotorAmps Output....................................................................29
3.10 Fault Diagnosis ..........................................................................30
4. RELAYTESTING
4.1 CommissioningTests.................................................................31
4.2 Overloads ..................................................................................33
4.3 SinglePhasing...........................................................................34
4.4 Ground Fault/Earth Leakage .....................................................35
4.5 Thermistor .................................................................................37
4.6 4-20 mA Output ......................................................................... 38
4.7 Routine MaintenanceVerification .............................................. 39
4.8 ProblemTroubleshooting...........................................................40
5. THEORY OF OPERATION
5.1 Hardware ...................................................................................42
5.2 Firmware....................................................................................45

1
1. INTRODUCTION
1.1 MOTOR PROTECTION REQUIREMENTS
Three phase AC motors have become the workhorse of mod-
ern industry. Although motors are generally reliable devices,
many different causes ranging from abnormal conditions to op-
erator abuse can result in premature failure.Newer motors also
tend to be designed much closer to the normal operation limits
allowing less margin for abuse.
Sophisticated electronic relays are now normally used on large
high voltage motors to protect against a wide range of possible
fault conditions. High cost has precluded the use of these re-
lays on less expensive motors. In these applications, a simple
thermal overload is usually used.While inexpensive, these de-
vices only give limited protection under one type of fault condi-
tion — overloads.
The PROTECT 4A relay is designed to provide protection
against the four main causes of motor failure: overloads, single
phasing, ground faults (earth leakage) and overheating (ther-
mistor sensing).The Protect 4A relay is economical enough in
price that it can be used with low and medium voltage motors,
bridging the gap between expensive, sophisticated relays and
economical thermal overloads which are of limited effectiveness.
While no relay can prevent normal wear on the motor, the Pro-
tect 4A has been optimized to give maximum motor life without
unnecessary production shutdown from overprotection.Controls
are simple and self explanatory for ease of use.
Current sensing is achieved through the use of separate phase
and ground fault CTs connected directly to the PROTECT 4A
relay.Three 5 amp or 1 amp secondary CTs are used to sense
motor phase currents. The three phase current wires pass
through the window of a 2000:1 CT for ground fault sensing.

2
FIGURE1-1 PROTECT4ATYPICAL SYSTEM CONNECTION

3
1.2 PROTECT 4A FEATURES
A microcomputer housed in a rugged, industrial package al-
lows the Protect 4A to provide accurate, economical protection
in a unit that will outlast the life of the motor. Since many new
factories are using programmable controllers as automation in-
creases, a 4-20mA output of motor current is also provided elimi-
nating the need for an additional transducer.This output gives
a direct reading of motor current.
Fault diagnosis after a trip is displayed on front panel indica-
tors. This will allow operators and electricians to rapidly isolate
and correct problems. It is possible to verify correct operation
of an installed Protect 4A relay to ensure that the motor protec-
tion is functioning properly.
One Protect 4A relay is required per motor. Phase and ground
fault currents are monitored through current transformers so that
motors of any line voltage can be protected.The relay is used
as a pilot device to cause a contactor or breaker to open under
fault conditions;that is, it does not carry the primary motor cur-
rent. Figure 1-1 shows how the Protect 4A is connected into a
system for complete motor protection.
TABLE 1-1 PROTECT 4A FEATURES
FEATURES
•Fault Diagnosis
•4–20mA Output of Motor
Current
•Overload Status Indicator
•Economical
•Compact — Plug In
•Universal Models
Simplify Spares
PROTECTION
•Overloads
(8 Time Curves)
•Locked Rotor/Stall
•Mechanical Jam
•Multiple Starts
•Single Phasing
•Ground Fault/Earth
Leakage (Trip or indica-
tion only)
•Overheating (Thermistor
Sensing)

4
1.3 TYPICAL APPLICATIONS
Versatile features make the Protect 4A an ideal choice in a wide
range of motor applications.It should be considered for these
and other typical uses:
1) Basic protection on low and medium voltage motors. The
lowest horsepower selected for protection in an installa-
tion will depend on frequency of motor failure.
2) Protection of motors and equipment from operator abuse
3) Personnel safety from shock hazard using sensitive ground
fault settings to detect winding shorts or leakage current
from moisture in mines.
4) Fault indication of ground fault without shutdown to warn
that corrective maintenance is required.
5) Mechanical protection of gears, pumps, fans, saw mills, cut-
ters and compressors against mechanical jam.
6) Simplified spare parts stocking using one universal model
to cover all motor sizes and settings.
7) Output of motor current suitable for programmable controller
interface (4–20mA).
The motor phase currents are sensed by 3 conventional 1 amp
or 5 amp secondary current transformers (CTs). If ground fault
sensing is required then a separate zero sequence ground fault
CT, through which all 3 phase conductors pass, is required.This
CT is available in 2 sizes:HGF-3 (3½" diameter window) or HGF-
5 (5½" diameter window).
Note: Ground fault sensing only works on systems that are solid
or resistance grounded. Ungrounded systems require an artifi-
cial ground, through the use of a zigzig transformer, for ground
fault sensing to work.

5
PHASE SENSING CURRENT TRANSFORMERS
Any standard 5 amp secondary 5 VA or greater CT can be
used. 3 phase CTs per PROTECT 4A are required. 1 amp
CT operation available on special order.
PART NO. DESCRIPTION
CT-100:5 100:5
CT-150:5 150:5
CT-200:5 200:5
CT-250:5 250:5
CT-300:5 300:5
CT-500:5 500:5
CT-1000:5 1000:5
1.4 ORDER CODE
TABLE 1-2 RELAY ORDER CODE
RELAY PROTECT 4A — 120
PART NO. DESCRIPTION
PROTECT 4A Standard relay
— 120 120 VAC control voltage
— 240 240 VAC control voltage
GROUND FAULT CURRENT TRANSFORMERS
1 required for ground fault sensing:
PART NO. DESCRIPTION
HGF3 3½" Window 2000:1
HGF5 5½" Window 2000:1

6
1.5 TECHNICAL SPECIFICATIONS
TABLE 1-3 TECHNICAL SPECIFICATIONS
FULL LOAD CURRENT
50-100% PHASE CT RATING
INPUT: 0-8 TIMES MAXIMUM RANGE
CURRENT
FREQUENCY: 48-62 Hz, 3 PHASE SINUSOID
MAXIMUM INPUT: 8 TIMES FULL LOAD 25 SECONDS
12 TIMES FULL LOAD 2 SECONDS
FULL LOAD CONTROL — AMPS
RANGE: 50-100% PHASE CT RATING
CALIBRATED VALUE:3 PHASE SINEWAVE-RMS
EQUIVALENT
PICKUPACCURACY: ±5% FULLSCALE
OVERLOAD TIMES: ±10%CURVEVALUE
MECHANICAL JAM: ACTIVATED AT 3 TIMES FULL LOAD
SETTING IF ENABLED.
NOMINAL DELAY — 1 SECOND
SINGLE PHASE
ACTIVATION: SEVERE UNBALANCE/SINGLE
PHASE DEFEATED IF MOTOR
AVERAGE CURRENT < 40% FULL
LOAD SETTING
TRIP DELAY: 5 SECONDS ±2 SECONDS
THERMISTOR INPUT
HOT TRIP
RESISTANCE: 2800-3300 OHMS
COLD RESET
RESISTANCE: 250 OHMS MAX
TRIP DELAY: 3SECONDS ±1 SECOND
THERMISTOR MEMORY MODEL
ACTIVE: MOTOR RUNNING/STOPPED WITH
CONTROL POWER
CLEAR: POWER ON OR RESET AFTER TRIP
COOL RATE: 5 MINUTES TO CLEAR MEMORY
@10 SEC STALL SETTING
RESET: NOLOCKOUT ON TRIP
GROUND FAULT/EARTH LEAKAGE
TRIP LEVEL: 1-10A ±15% PRIMARY CURRENT
FULL SCALE
(0.5A MAX WITH CONTROL FULLY
ANTI-CLOCKWISE)
TRIP DELAY: TIMES AT < 25% PICKUP
THRESHOLD
30ms 7-30ms TYPICAL 30ms MAX
50,100ms: ±15ms
200, 300, 500, 750,
100ms:±15%
MOTOR AMPS OUTPUT
OUTPUT CURRENCY: 4 mA = 0 AMPS
20 mA = PHASE CT RATING
ACCURACY: LINEAR ±5% FULL SCALE
MAXIMUMLOAD
RESISTANCE: 350 OHMS
SATURATION
OUTPUT: 30mAMAX
OUTPUT CONTACTS
TYPE: SINGLE FORM C NO/NC
SILVER CADMIUM OXIDE
RATINGS: STANDARD PILOT DUTY
120/240 VAC 10 AMPS
@ 80% P.F.
360VA
28 VDC 10 AMPS
CONTROL POWER
120VAC INPUT RANGE: 85-140 VAC
240VAC INPUT RANGE: 170-280 VAC
FREQUENCY: 48-62 Hz
POWER: 5VA
PHYSICAL SHIPSHIP
SHIPSHIP
SHIP CARCAR
CARCAR
CARTONTON
TONTON
TON
PRODUCTPRODUCT
PRODUCTPRODUCT
PRODUCT WEIGHTWEIGHT
WEIGHTWEIGHT
WEIGHT DIMENSIONSDIMENSIONS
DIMENSIONSDIMENSIONS
DIMENSIONS
PROTECT 4A 4 lbs 5¼" × 5¼" × 7½"
8.8 kg 133mm×133mm ×191mm
HGF3 2.2 lbs 2½" × 6½" × 6½"
1 kg 64mm× 165mm× 165mm
HGF5 3.8 lbs 3"× 8" ×9"
1.5 kg 76mm× 204mm× 228mm
ENVIRONMENT
TEMPERATURE RANGE
–10°C — +60°C
CERTIFICATION: CSA

7
2. INSTALLATION
2.1 PHYSICAL DIMENSIONS
Dimensions of the Protect 4A relay and mounting components
are shown in fig.2-1.Both the clear cover and the terminal board
are detachable from the relay.The case is made of rugged plastic
with a clear cover for viewing indicators and control settings.
Phase CTs with 1 amp or 5 amp secondaries should be used.
These can be standard CTs which are user supplied. Dimen-
sions for CTs available from Multilin are shown in figure 2.2. If
zero sequence ground fault detection is required, the appropri-
ate ground fault CT shown in figure 2-3 must be installed.
FIGURE 2-1 RELAY DIMENSIONS
REAR VIEW

8
FIGURE 2-2 PHASE CT DIMENSIONS
FIGURE 2-3 GROUND FAULT CT DIMENSIONS

9
2.2 MOUNTING
Normally the Protect 4A relay will be mounted on a panel or
motor control center door so that the indicators can be viewed
and the reset button is directly accessible. A square cutout is
made in the door as shown in fig.2-1.The relay is then placed
in the cutout and two mounting brackets are installed to hold it
in place as shown in fig 2-4.The terminal board socket is wired
and plugged into the back of the relay. A spring retaining clip
that goes into slots on the back of the relay is provided with the
relay.This should be installed to prevent the terminal board from
working loose.
If it is desirable to let operators reset a tripped Protect 4A relay,
the cover plate should be mounted with the reset hole plug over
the reset switch.If it is in inconvenient to remove the plug when
resetting the unit is necessary, an extender shaft can be ob-
tained that protrudes through the front cover hole and fits over
the reset button.Tamper proof screws are also available for at-
taching the cover to prevent access to the controls or the reset
switch by unqualified personnel.
FIGURE 2-4 RELAY MOUNTING

10
2.3 EXTERNALWIRING
A typical wiring diagram for the Protect 4A relay is shown in
figure 2-5. Connections are made to the terminal board pro-
vided which is then plugged onto the Protect 4A relay. Protect
4A relays are interchangeable and can be quickly replaced by
a standard spare unit regardless of the motor current range.
Separate phase and ground fault CTs are wired directly to the
back of the Protect 4A.It is recommended that the ground fault
CT wires be twisted together to minimize noise pickup.
FIGURE 2-5 TYPICALWIRING DIAGRAM

11
2.4 CONTROL POWER
Control power must be applied to the Protect 4A relay before
energizing the motor for correct operation. Supply voltage can
be selected as 120VAC or 240VAC by a selector switch on the
power supply board.
The supply voltage for which the relay is set will be clearly mark-
ed on the wiring diagram label attached to the outside of the
relay. If the supply voltage is to be changed, the cover must be
removed and the selector switch shown in fig. 2-6 set accordingly.
When changing the supply voltage be sure to mark the new
voltage on the terminal label for future reference.
Full accuracy of the Protect 4A relay will be maintained over a
wide range of supply voltages which are typically found in in-
dustrial environments (85-140VAC) or (170-275VAC) 48-62Hz.
When the control voltage drops below the minimum voltage,
the PROTECT 4A output contacts go into the trip condition to
provide fail-safe operation. Whenever control power is applied
to the Protect 4A, it will come on in the state present at loss of
power.
Since the reset for the Protect 4A relay is electrical, control power
must be applied when the relay reset button is pushed.
FIGURE 2-6 CONTROL VOLTAGE SELECTION

12
2.5 TRIP CONTACTS
One set of form C normally open/normally closed contacts are
provided for switching up to 240VAC, 10 amps, 360VA which
should be adequate for most loads. Silver cadmium oxide con-
tacts are provided because of their ability to withstand high in-
rush inductive loads.Connection of the trip contacts to the motor
contactor or breaker is shown in the typical wiring diagram fig-
ure 2-5.
When the relay is ready for motor starting, the contacts for termi-
nals 1, 2, 3 will be as shown in figure 2-5. When the relay trips,
or if control power is lost, the contacts will change to the oppo-
site condition. However, if this change occurred from lost con-
trol power, the main relay will return to its normal operating state
when power is re-applied, without having to reset the relay.
The output contacts can be returned to the untripped state by
pressing the reset button or by selecting the auto reset option
(section 2.9.1.).
2.6 THERMISTOR INPUT
In order to use the thermistor sensing feature the motor being
protected must have a suitable thermistor sensor embedded in
the stator winding.This is normally fitted when the motor is built
or rewound although it may be possible to retrofit a thermistor
into the end turns of some motors. Thermistors exhibit a non-
linear characteristic and the Protect 4A is designed to match a
characteristic similar to that shown in figure 2-7.The actual trip
temperature of the thermistor is specified when it is ordered.
Consult the factory for recommended thermistor types that will
work with the Protect 4A relay.
If three thermistors are installed in the motor connect them in
series as shown in figure 2-8. When combining several ther-
mistors in series, care should be taken to ensure that the maxi-
mum cold resistance including wiring resistance does not
exceed the trip temperature resistance. If any thermistor over-
heats in this configuration the relay will trip.Should no thermis-
tor be installed in the motor it is not necessary to make any

13
connection to terminals 5 and 6. A no sensor detector will pre-
vent the relay from tripping.Alternately, a jumper can be placed
across these two terminals. The Protect 4A relay is not suit-
able for use with RTDs (resistance temperature detectors).
If no thermistor is used, put a jumper between terminals 5 and
6 to prevent nuisance tripping from noise. Shielded wire should
be used for the thermistor input especially if the wiring is near
high current conductors or if the motor is remotely situated. Max-
imum shield effectiveness is obtained if the shield is grounded
at one end only.
FIGURE 2-7 THERMISTOR CHARACTERISTIC
FIGURE 2-8 THERMISTOR CONNECTION

14
2.7 PROGRAMMABLE CONTROLLER OUT-
PUT
In many installations an output of motor current into a program-
mable controller is desirable. Terminals 4 (+ VE) and 5 (-VE)
provide a DC output of 4-20mA proportional to motor current.
The 20mA output is obtained at the rated CT ratio. For exam-
ple, if a 600:5 CT is used, at 600 Amps the output would be
20mA. The output saturates below 30mA during overloads to
prevent damage to the programmable control.
2.8 TAMPER PROOF COVER
If limited access to the Protect 4A controls is desired to prevent
settings from being altered by operators, tamper proof screws
and a special installation tool can be ordered.The normal cover
screws are replaced with these special screws so that the cover
cannot be removed without the tool. The cover can also be ro-
tated 180 degrees and a plug placed over the reset button hole.
This prevents access to the reset button so that only qualified
personnel can reset the relay once it has tripped.
2.9 FIELD OPTIONS
It is possible to change some features on the relay in the field
for specific applications.Refer to the internal switch setting loca-
tion diagram fig. 2.9 to set the field options.

15
FIGURE 2-9 FIELD PROGRAMMABLE OPTIONS
2.9.1 AUTO RESET
Normally a Protect 4A relay will only reset after a trip by push-
ing the reset button.If it is required to automatically reset when-
ever a trip occurs, set switch S306 on.The relay will automatically
reset about 5 seconds after tripping. Note that the indicators
will also reset so that the cause of the trip will not be apparent.
If auto reset is used, ensure that the motor can only be restarted
by an operator once the fault has been cleared.

16
2.9.2 MECHANICAL JAM
Overloads will normally cause a trip according to the overload
curves of fig.3-2. In some situations it may be desirable to pro-
tect associated mechanical equipment against a jam while runn-
ing.Setting switch S303 off will cause the relay to trip whenever
the current rises above 3 times the FULL LOAD—AMPS con-
trol setting for one second while the motor is running
The Protect 4A automatically defeats mechanical jam during
the high starting inrush current but enables this option (if switch
S303 is off) as soon as the inrush current drops below the FULL
LOAD AMPS setting.This feature is especially useful in appli-
cations such as pumps and fans where overloads are not part
of normal operation.Mechanical jam will activate the overload
indicator.
2.9.3 GROUND FAULT INDICATION ONLY
In some resistance grounded systems a single ground fault
detector is used to monitor a complete bus feeding numerous
motors.If one of the motors develops a ground fault, an alarm
condition is registered on the central ground fault monitor but
the motors may be allowed to continue running to prevent a
production shut down. This is possible since the ground fault
current is resistance limited, however the faulty motor should
be repaired as soon as possible because a second ground fault
on another phase could cause a phase to phase short circuit
resulting in extensive damage. If the motors don’t have indi-
vidual ground fault protection, the whole bus must be sched-
uled for a convenient shutdown and each motor checked until
the faulty one is found.
A ground fault above the trip settings will normally cause the
Protect 4A to trip with a ground fault indication. Setting switch
S304 off will cause the ground fault indicator to activate but will
inhibit a trip due to a ground fault. If each motor is equipped
with a Protect 4A and this feature is selected, when the central
monitor registers a ground fault, it is only necessary to look at
each Protect 4A to locate the faulty motor.The defective motor
can then be shut down and repaired when convenient without
shutting down the rest of the bus and testing every motor.

17
This scheme is not suitable for solidly grounded systems since
any motor which develops a ground fault should be shut down
immediately due to the high current that can flow.
Once the ground fault indicator is set it can only be reset by
pressing the reset button.This makes it particularly useful for
detecting momentary ground faults due to initial insulation break-
down and arcing or excessive moisture in mines,
2.9.4 SINGLE PHASE DEFEAT
Systems such as variable speed controllers may produce non-
sinusoidal waveforms that may cause nuisance tripping of the
single phase detection. If this is a problem, the single phase
protection may be defeated by setting switch S305 off.
2.9.5 FACTORY SERVICE
Switches S301/S302 are used for factory calibration. They
should be left off for correct operation.
2.10 ENVIRONMENT
Precision components and rugged industrial packaging are us-
ed to ensure that Protect 4A relays will perform accurately and
reliably over a wide range of conditions typical of industrial en-
vironments around the world.Some of the features incorporated
into the Protect 4A design to ensure trouble free operation and
useful life longer than the motor being protected are listed in
table 2-1.
TABLE 2-1 PROTECT 4A ENVIRONMENTAL FEATURES
•Transient protection/filtering on inputs and outputs
•Crystal controlled time delays for accuracy with tem-
perature/aging
•Precision IC voltage references for stable accuracy
•Wide temperature range –10°C to +60°C