ABB OTM C 21D User manual

Automatic Transfer Switch OTM_C_21D
Installation and operating instructions
34OTM_C_21D rev. B / EN / 1SCC303015M0201

Read through this instruction book carefully before working on the switch, and keep this instruction
book safe for later reference.
The images provided in this instruction book are for illustration only and may not match the actual
product exactly.
This instruction book is subject to change for product updates without prior notice.

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1SCC303015M0201 l ABB Installation and operating instructions, 34OTM_C_21D rev. B
Contents
Contents
1. Symbols & Terms.........................................................................................................4
1.1 Use of symbols......................................................................................................................................4
1.2 Explanations of abbreviations and terms.............................................................................................4
2. Product overview.........................................................................................................5
2.1 Product overview and packing .............................................................................................................5
2.2 OTM_C_21D switching sequence......................................................................................................... 6
2.2.1 Line 1 Priority (default mode) ............................................................................................. 6
2.2.2 No line priority.....................................................................................................................6
2.2.3 Manual back switching mode ............................................................................................7
3. Quick start ...................................................................................................................8
3.1 Operating the switch manually (local operation) .................................................................................8
3.2 Automatic operation..............................................................................................................................9
3.3 System testing..................................................................................................................................... 10
3.3.1 Local test...........................................................................................................................10
3.3.2 Remote test....................................................................................................................... 10
3.4 Locking ................................................................................................................................................11
3.4.1 Locking the electrical operation.......................................................................................11
3.4.2 Locking the manual operation .........................................................................................11
4. Interface and Settings...............................................................................................12
4.1 Buttons ................................................................................................................................................12
4.2 LEDs ....................................................................................................................................................12
4.3 Rotary switch setting ..........................................................................................................................13
4.4 Dip switch setting................................................................................................................................14
4.5 Terminal outputs and inputs ...............................................................................................................15
5. Technical data............................................................................................................16
6. Installation .................................................................................................................16
6.1. Installation method.............................................................................................................................16
6.2. Installation dimensions ...................................................................................................................... 18
7. Optional accessories.................................................................................................19
7.1 Bridging bars .......................................................................................................................................19
7.2 Terminal shrouds .................................................................................................................................20
7.3 Auxiliary contact blocks...................................................................................................................... 21
8. Maintenance and common troubleshooting ............................................................22
8.1 Maintenance ........................................................................................................................................22
8.2 Common troubleshooting ...................................................................................................................22
9. Appendix....................................................................................................................23
9.1 Wiring diagram .................................................................................................................................... 23

1SCC303015M0201 l ABB Installation and operating instructions, 34OTM_C_21D rev. B
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1. Introduction
OTM_C_21D 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
EMERG OFF (fire control
system)
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 Switching delay
TBs Back switching delay
OV Adjustable overvoltage threshold
UV Adjustable undervoltage threshold
1. Symbols & Terms
Caution:
provides important information or warns about a situation that may have a detri-
mental effect on equipment.
General warning:
warns about a situation where something other than electrical equipment may
cause physical injury to a person or damage to equipment.
Information:
provides important information about the equipment.
1.1 Use of symbols
1.2 Explanations of abbreviations and terms
Risk of Electric shock:
warns about a situation where a hazardous voltage may cause physical
injury to a person or damage to equipment.
Table 1. Explanations of abbreviations and terms

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1SCC303015M0201 l ABB Installation and operating instructions, 34OTM_C_21D rev. B
2. Product overview
2. Product overview
2.1 Product overview and packing
The OTM_C_21D 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 undervoltage detection, transfer delays, generator start and stop, and remote
test function. Source transfer can be performed using a manually 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.
Figure 1. OTM_C_21D automatic transfer switch
1. Handle for manual operation 7. Locking latch for releasing the handle
2. Place for auxiliary contact blocks and locking electrical control
3. Push button 8. Locking clip for locking manual operation
4. Mimic panel 9. Dip switches
5. Voltage sensing connections 10. Rotary switches
6. Locking clip for padlock 11. Connecting terminal
10 4 5
7
11
98 1 362
The standard package includes:
1. automatic transfer switch, 2. handle, 3. handle storage clip and 4. terminal plug.

1SCC303015M0201 l ABB Installation and operating instructions, 34OTM_C_21D rev. B
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2. Product overview
2.2 OTM_C_21D switching sequence
2.2.1 Line 1 Priority (default mode)
The switching sequence of OTM_C_21D can be summarized in following steps:
• An anomaly occurs on the Line 1 (LN1)
• Switching delay Ts, in case of phase-loss, overvoltage and undervoltage conditions
• Generator start, immediate start generator in case of black-out, in case of phase-loss,
overvoltage or undervoltage after switching delay Ts. (If Generator mode is selected)
• Change-over switch (Switch I) to the position 0
• Change-over switch (Switch II) to the position II
And the back switching sequence can be summarized in the following steps:
• The Line 1 will start the normal functioningl Back switching 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
2.2.2 No line priority
The switching sequence of OTM_C_21D can be summarized in following steps:
• An anomaly occurs on the Line 1 (LN1)
• Switching delay Ts, in case of 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 back switching 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)
• Back switching delay
• Change-over switch (Switch II) to the position 0
• Change-over switch (Switch I) to the position I

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1SCC303015M0201 l ABB Installation and operating instructions, 34OTM_C_21D rev. B
2. Product overview
Figure 3. Automatic Switching Sequences in OTM_C_21D, No line priority
Generator is disabled in no line priority. Keep generator off in this mode.
2.2.3 Manual back switching mode
The switching sequence of OTM_C_21D can be summarized in following steps:
• An anomaly occurs on the Line 1 (LN1)
• Switching delay Ts, in case of phase-loss, overvoltage and undervoltage conditions
• Generator start, immediate start generator in case of black-out, in case of phase-loss,
overvoltage or undervoltage after switching delay Ts. (If Generator mode is selected)
• Change-over switch (Switch I) to the position 0
• Change-over switch (Switch II) to the position II
And the back switching 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
Figure 4. Automatic Switching Sequences in OTM_C_21D, Manual back switching mode

1SCC303015M0201 l ABB Installation and operating instructions, 34OTM_C_21D rev. B
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3. Description
3. Quick start
3.1 Operating the switch manually (local operation)
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.
Before powering on the transfer switch, please manually operate it to ensure it
can operates and moves normally.
Then power supply is normal and without the handle attached or EMRG
OFF signals, the switch will be in automatic mode and switch to the primary
line upon initial power-up. Keep the handle attached if you do not want the
switch to be in automatic mode upon initial power-up.
When the handle is attached, the switch will automatically be in “manual
mode” with the automatic operation disabled.
Do not tamper with wires when the transfer switch is powered on.
Figure 5. Operating the switch manually

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1SCC303015M0201 l ABB Installation and operating instructions, 34OTM_C_21D rev. B
3. Description
3.2 Automatic operation
OTM_C_21D 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.
If handle is not inserted
1. If “AUTO” LED blinks, press “AUTO” button and the “AUTO” LED will be ON, indicating
automatic mode.
2. Automatic operation includes three operating modes: Line 1 priority (factory default setting),
No line priority, and manual back switching mode.
Figure 6. Selecting the automatic transfer OTM_C_21D switch to Auto Mode
2
1
3

1SCC303015M0201 l ABB Installation and operating instructions, 34OTM_C_21D rev. B
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3. Description
3.3 System testing
3.3.1 Local test
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.
3.3.2 Remote 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_C_21D 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 Position O àto Position II àto Position O àto
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_C_21D automatically returns to the automatic
mode (“AUTO” LED is on).
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.