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. B / 1SCC303015M0201 / EN

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Table of contents
2
003 – 004 Symbols & Terms
005 – 008 Product overview
009 – 012 Quick start
013– 016 Interface and Settings
017 Technical data
018 – 020 Installation
021 – 022 Optional accessories
023 Maintenance and common troubleshooting
024 Appendix

3
AUTOMATIC TRANSFER SWITCH, OTM_C_21D
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Symbols & Terms
Risk of Electric shock: Warns about a situation where a hazardous voltage may cause
physical injury to a person or damage to equipment.
General warning: Warns about a situation where something other than electrical
equipment may cause physical injury to a person or damage to equipment.
Caution: Provides important information or warns about a situation that may have a
detrimental effect on equipment.
Information: Provides important information about the equipment.
Table 1. Explanations of abbreviations and terms
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Explanations of abreviations and terms
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

4AUTOMATIC TRANSFER SWITCH, OTM_C_21D
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Product overview
Product overview
The OTM_C_21D automatic transfer switch can be
used as a source transfer switch in a threephase or
single-phase networks. Monitored conditions are,
no-voltage, phase-loss, overvoltage and under-
voltage detection, transfer delays, generator start
and stop, and remote test function.
Source transfer can be performed using a manu-
ally 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.
The standard package includes:
1. automatic transfer switch, 2. handle, 3. handle storage clip and 4. terminal plug.
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
10 4 5
7
11
9
8 1 3 6 2

5
AUTOMATIC TRANSFER SWITCH, OTM_C_21D
OTM_C_21D switching sequence
Line 1 Priority (default mode)
The switching sequence of OTM_C_21D can be
summarized in following steps:
The back switching sequence can be summarized
in the following steps:
• The Line 1 will start the normal functioning
• 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
LN1
LN2
Switch I status
Switch II status Ts TBs
• An anomaly occurs on the Line 1 (LN1)
• Switching delay Ts, in case of phase loss, over-
voltage 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

6AUTOMATIC TRANSFER SWITCH, OTM_C_21D
• An anomaly occurs on the Line 1 (LN1)
• Switching delay Ts, in case of phase-loss, over-
voltage and undervoltage conditions
• Change-over switch (Switch I) to the position 0
• Change-over switch (Switch II) to the position II
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
Figure 3. Automatic Switching Sequences in OTM_C_21D, No line priority
LN1
LN2
Switch I status
Switch II status Ts TBs
Generator is disabled in no line priority.
Keep generator off in this mode.
The switching sequence of OTM_C_21D can be
summarized in following steps:
No line priority

7
AUTOMATIC TRANSFER SWITCH, OTM_C_21D
• An anomaly occurs on the Line 1 (LN1)
• Switching delay Ts, in case of phase-loss, over-
voltage and under voltage conditions
• Generator start, immediate start generator in
case of black-out, in case of phase-loss, over-
voltage 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
Figure 4. Automatic Switching Sequences in OTM_C_21D, Manual back switching mode
LN1
LN2
Switch I status
Switch II status Ts
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 trans ferred
manually back to position I
The switching sequence of OTM_C_21D can be
summarized in following steps:
Manual back switching mode

8AUTOMATIC TRANSFER SWITCH, OTM_C_21D
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Quick start
To operate the switch manually:
1. Attach the handle to the switch panel. You can
attach the handle in any position.
Figure 5. Operating the switch manually
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.
Before powering on the transfer switch, please manually operate it to ensure it can oper-
ates 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.
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.

9
AUTOMATIC TRANSFER SWITCH, OTM_C_21D
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
Automatic operation
OTM_C_21D must be in automatic mode and the
“AUTO” LED is on in order that the switch can per-
form automatic transfer cycles according to the
preset operating 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.
System testing
Local test
In automatic mode, “AUTO” LED is ON and you
can transfer the switch using I, O, and II push but-
tons on the front panel of the switch. Press
“AUTO” button to return the automatic operation.
2
1
3

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.
e.g., when the switch is in Position I:
Enter test signals; the switch transfers to
Position O à to Position II à to Position O à to
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).
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.