ABB OTM C 21D User manual

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INSTALLATION AND OPERATING INSTRUCTION
Automatic Transfer Switch
OTM_C_21D
— Automatic Transfer switch 34OTM_C_21D rev. E / 1SCC303015M0201 / EN

2AUTOMATIC TRANSFER SWITCH, OTM_C_21D
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Table of contents
1. SYMBOLS & TERMS 3
2. PRODUCT OVERVIEW 4
3. QUICK START 78
4. INTERFACE AND SETTINGS 17
5. TECHNICAL DATA 22
6. INSTALLATION 23
7. OPTIONAL ACCESSORIES 26
8. MAINTENANCE AND COMMON
TROUBLESHOOTING 29
9. APPENDIX 30

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AUTOMATIC TRANSFER SWITCH, OTM_C_21D
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1. Symbols & Terms
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1.1 Use of symbols
Risk of Electric shock: warns about a situation where a hazardous voltage may cause phys-
ical injury to a person or damage to equipment.
General warning: warns about a situation where something other than electrical equip-
ment may cause physical injury to a person or damage to equipment.
Caution: provides important information or warns about a situation that may have a detri-
mental effect on equipment.
Information: provides important information about the equipment.
Table 1. Explanations of abbreviations and terms
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1.2 Explanations of abreviations and terms
OTM_C21D Automatic transfer switch, the type name
LN1-Switch I Power supply line, e.g. the primary line
LN2-Switch II Power supply line, e.g. the secondary line used in emergency cases
EMRG OFF Used to drive the automatic transfer switch transfers to the “O” position when
receiving EMRG OFF signal.
AUTO Automatic mode
Remote test A sequence to test the functionality of the automatic transfer switch
Ts Transfer delay
TBs Return delay
OV Adjustable overvoltage threshold
UV Adjustable undervoltage threshold

4AUTOMATIC TRANSFER SWITCH, OTM_C_21D
The OTM_C21D automatic transfer switch can be
used as a source transfer switch in a three-phase
or single-phase networks. Monitored conditions
are, no-voltage, phase-loss, overvoltage and un-
dervoltage detection, transfer delays, generator
start and stop, and remote test function. Source
transfer can be performed using a manually
The standard package includes:
1. automatic transfer switch, 2. handle, 3. handle storage clip 4. terminal plug, 5. mounting kit
Figure 1. OTM_C_21D automatic transfer switch
1. Handle for manual operation
2. Place for auxiliary contact blocks
3. Push button
4. Mimic panel
5. Voltage sensing connections
6. Locking clip for padlock
7. Locking latch for releasing the handle and
locking electrical control
8. Locking clip for locking manual operation
9. Dip switches
10. Rotary switches
11. Connecting terminal
12. Modbus RTU access
10 4 5
7
11
9
8 1 3 6 2
12
operated handle, locally using push buttons or
fully automatically. The automatic mode includes
several operating methods: Line 1 priority, no line
priority and manual back switching mode. OTM_
C21D can achieve communication function by
using the optional external Modbus RTU module.
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2. Product overview
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2.1 Product overview and packing

5
AUTOMATIC TRANSFER SWITCH, OTM_C_21D
And the return sequence can be summarized in
the following steps:
•The Line 1 will start the normal functioning
•Return delay TBs
•Change-over switch (Switch II) to the position 0
•Change-over switch (Switch I) to the position I
•Generator stop delay Gs
•Generator stop
Figure 2. Automatic Switching Sequences in OTM_C_21D, Line 1 priority
The transfer sequence of OTM_C21D can be sum-
marized in following steps:
•An anomaly occurs on the Line 1 (LN1)
•Generator start, immediately start generator in
case of black-out, phase-loss, overvoltage or
undervoltage (If Generator mode is selected)
•The Line 2 start the normal functioning,
transfer delay Ts
•Change-over switch (Switch I) to the position 0
•Change-over switch (Switch II) to the position II
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2.2 OTM_C21D switching sequence
2.2.1 Line 1 Priority (default mode)

6AUTOMATIC TRANSFER SWITCH, OTM_C_21D
The transfer sequence of OTM_C21D can be sum-
marized in following steps:
•An anomaly occurs on the Line 1 (LN1)
•Transfer delay Ts, in case of black-out, phase-
loss, overvoltage and undervoltage conditions
•Change-over switch (Switch I) to the position 0
•Change-over switch (Switch II) to the position II
And the return sequence can be summarized in
the following steps:
•The Line 1 will start the normal functioning
•Change-over switch stays in position II
•An anomaly occurs on the Line 2 (LN2)
•Return delay TBs
•Change-over switch (Switch II) to the
position 0
•Change-over switch (Switch I) to the position I
Figure 3. Automatic Switching Sequences in OTM_C_21D, No line priority
Generator can not be used in no line priority. Keep Dip switch “GEN SEL” setting “0”
in this mode.
2.2.2 No line priority

7
AUTOMATIC TRANSFER SWITCH, OTM_C_21D
The transfer sequence of OTM_C21D can be sum-
marized in following steps:
•An anomaly occurs on the Line 1 (LN1)
•Generator start, immediately start generator
in case of black-out, phase-loss, overvoltage or
undervoltage (If Generator mode is selected)
•The Line 2 start the normal functioning,
transfer delay Ts
•Change-over switch (Switch I) to the position 0
•Change-over switch (Switch II) to the
position II
Figure 4. Automatic Switching Sequences in OTM_C_21D, Manual return mode
And the return sequence can be summarized in
the following steps:
•The Line 1 will start the normal functioning
•Change-over switch stays in position II
•An anomaly occurs on the Line 2 (LN2)
•Change-over switch stays in position II
•Change-over switch can be transferred
manually back to position I
2.2.3 Manual return mode

8AUTOMATIC TRANSFER SWITCH, OTM_C_21D
To operate the switch manually:
1.Attach the handle to the switch panel. You can
attach the handle in any position.
2.When the handle is attached, the automatic
transfer switch will automatically be in Manual
mode and won’t operate automatically in case
of line failure. The AUTO LED on the mimic panel
is OFF.
Figure 5. Operating the switch manually
When the handle is inserted into the switch, the switch will enter “manual mode” with the
automatic operation disabled.
Do not adjust wires when the transfer switch is being energized.
Before the power-on operation of the transfer switch, please operate the switch manually
to confirm it is in normal function.
With the power supply function in “normal” and without the handle inserted and EMRG OFF
signals, the initially energized switch will enter automatic mode and transfer to the main
line. Keep the handle inserted if you do not want the switch to be in automatic mode upon
initial energization.
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3. Quick start
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3.1 Operating the switch manually (local operation)

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AUTOMATIC TRANSFER SWITCH, OTM_C_21D
OTM_C21D must be in automatic mode and the
“AUTO” LED is on in order that the switch can
perform automatic transfer cycles according to
the pre-set operating mode.
To operate the switch electrically:
•If the handle inserted
1. Press handle locking clip and remove the handle
from the switch.
2. Press “AUTO” button and the “AUTO” LED will
be ON, indicating automatic mode.
Figure 6. Selecting the automatic transfer OTM_C_21D, switch to Auto Mode
2
1
3
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3.2 Automatic operation
•If handle is not inserted
1. If “AUTO” LED blinks, press “AUTO” button and
the “AUTO” LED will be ON, indicating auto-
matic mode.
2. Automatic operation includes three operating
modes: Line 1 priority (factory default setting),
No line priority, and manual return mode.

10 AUTOMATIC TRANSFER SWITCH, OTM_C_21D
Figure 7. Remote test connection in OTM_C_21D
In the test sequence, the main power supply circuit will be closed.
If the test sequence is interrupted due to power failure, the automatic transfer switch will
enter “automatic mode” after power recovery.
In automatic mode, “AUTO” LED is ON and you can
transfer the switch using I, O, and II push buttons
on the front panel of the switch.
Press “AUTO” button to return the automatic
operation.
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3.3 System testing
3.3.1 Local test
The procedure of the remote test is as follows:
1. Connect to the remote test signal according to
Figure 7.
2. Ensure that the OTM_C21D is in automatic
mode (“AUTO” LED is on).
3. Short circuit the remote test signal for at least
100 ms until the “AUTO” LED blinks to enter the
test mode. Under test mode, the automatic
transfer switch will simulate switching cycle
and finally return to its original position prior
to the activation of the test mode.
e.g., when the switch is in Position I:
Enter test signals; the switch transfers to
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Position I. Entering test signals is invalid before
the automatic transfer switch returns to its
original position.
Under test mode, press the “AUTO” button to
cancel test mode and return to automatic
mode. The “Auto” LED will be “ON” as normal.
4. After the remote test finishes, the OTM_C21D
automatically returns to the automatic mode
(“AUTO” LED is on).
3.3.2 Remote test