ComAp NPU Installation And Operation Instructions Manual

Software version 1.8, September 2003
Prague, Czech Republic
Copyright © 2003 ComAp s.r.o.
Written by Libor Šindelářl and Milan Vandírek

ComAp, spol. s r.o.

Světova 7, 180 00 Praha 8, Czech Republic
Tel: [phone], Fax: [phone]
E-mail: [e-mail], www.comap.cz

NPU Unit

Mains decoupling relay

Installation and Operation Instructions

User guide

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1. Contents

1. Contents 2

2. Technical Specification 3
NPU Technical Specification 4
NPU Mechanical Design 5

3. Installation 6
Power Supply 6
Analog Inputs 6
Output Relays 6
The NPU Unit Wiring Diagram 7

Connection NPU Unit to phase-to-neutral voltage 7
Connection NPU Unit to phase-to-phase voltage 8

4. Function 9
Protection types 9

Overvoltage protection 9
Undervoltage protection 9
Overfrequency protection 9
Underfrequency protection 9
Voltage assymetry protection 9

Vector shift supervision 9
Phase sequence supervision 10
Frequency measurement 10
Internal watchdog 10
Output Relays 10
Example: Evaluation of under voltage protection 11
Vector Shift Protection 12

5. Settings 14
Buttons 14
Display and LEDs 14
Parameters settings 14

6. Displayed Quantities and Parameters 15
Set A: 15

Default setting 16

Set B: 17

Default setting 17

7. Order codes 19

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2. Technical Specification

The NPU unit is designed for 3-phase mains protection. Operator can switch on/off available protections or
adjust limits and time delays for each protection.
Rated voltages are 100, 230, 400, 480 VAC selected by order - see order codes. Measuring voltage
frequency range is from 44 up to 68 Hz.
NPU power supply voltage can be in the range 90 ÷ 250 VAC or 16 ÷ 110 VDC selected by order - see
order codes.

NPU offers following protections:

• Over frequency protection

• Under frequency protection

• Over voltage protection

• Under voltage protection

• Phase sequence supervision

• Voltage asymmetry protection

• Vector shift supervision

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NPU Technical Specification

Parameter Specification

Dimensions 75 x 100 x 115 mm
Power supply
NPU XXX/YYY/230VAC
NPU XXX/YYY/24VDC

90 ÷ 250 VAC
16 ÷ 110 VDC

Power consumption c. 3 W
Insulation 4 kV
Elmg. Interference immunity According to IEC 50082-2
Elmg. Interference According to IEC 55022
Temperature range

-20 ÷ +70°C

Protection IP20
Rated voltage 100, 230, 400, 480 VAC (by the order)
Maximal voltage range Rated + 30 %
Rated frequency 50 / 60 Hz
Maximal frequency range 44 – 68 Hz
Accuracy of frequency measuring 0,2% from rated value (from 10% of rated voltage value)
Accuracy of voltage measuring

1% from rated value at rated frequency ± 10% and 25°C
1,5% over whole temperature range

Signal relay contacts

- max. switched voltage / current

- max. switched power

- rated voltage / current

- minimum load

- lifetime

250 V / 4 A
rezistive load: 1000 VA AC, 200 W DC
inductive load: 500VA AC, 25W DC
rezistive load: 250V / 4A AC
200V/0,1A DC, 24V 4A DC
inductive load: 250V / 2A AC
200V/0,1A DC, 24V 3A DC
1W / 1VA at U

min

> 10V

1x105 cycles
Overvoltage category Class. III
Time delay accuracy

0.2% +0÷30ms

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NPU Mechanical Design

The NPU is packaged in a plastic box for assembly on a mounting plate TS 35 (DIN rail 35 mm).
NPU could be also mounted with two screws M4 (with span 60mm) to a mounting board. For this
alternative it is necessary to take out and turn clamp on the rare side of the box.
NPU has four operating push-buttons. The SET button (for settings) can be protected with cover (fixed by
wire with two seals). The NPU has an LED display (four digits) and 10 LEDs for indication. Dimensions are
on the figure.

1

1

5

,

0

75,0

100,0

Set

NPU

PWR

ERR

L1

UU

U

f

L2

L3

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3. Installation

Power Supply

There are two types of NPU units – see chapter 7 – Order codes:
NPU XXX/YYY/230VAC power supply is in range 90 ÷ 250 VAC
NPU XX/YYY/24VDC power supply is in range 16 ÷ 110 VDC
Power supply polarity is not important in the case of DC power. The terminal PE is only as an anti­interference terminal.

Analog Inputs

The rated voltage (100, 230, 400, 480 VAC) is selected by order. Terminals are designed for connection of
either phase-to-phase or phase-to-neutral voltage measurement. For connection see wiring diagram.

Output Relays

See wiring diagram. Relays on figure are without supply voltage (failure situation)

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The NPU Unit Wiring Diagram

Connection NPU Unit to phase-to-neutral voltage

11 14 12 21 24 22 31 34 32 41 44 42 A1 PE A2

2L1 3L11L1 2L2 3L21L2 2L3 3L3 1L3

POWER SUPPLY SWITCHED CONTACTS

OF SIGNAL RELAYS

CONNECTION NPU UNIT TO PHASE-TO-NEUTRAL VOLTAGE

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Connection NPU Unit to phase-to-phase voltage

11 14 12 21 24 22 31 34 32 41 44 42 A1 PE A2

POWER SUPPLY SWITCHED CONTACTS

OF SIGNAL RELAYS

CONNECTION NPU UNIT TO PHASE-TO-PHASE VOLTAGE

L1
L2
L3
PE

2L1 3L1 1L1 2L2 3L2 1L2 2L3 3L3 1L3

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4. Function

Protection types

Overvoltage protection

The protection responds to raising the voltage above set threshold (A11, A12, A13) with it’s own delay
(A14). Limits can be set for any phase extra. By setting zero value the protection is switched off.

Undervoltage protection

The protection responds to voltage drop under set threshold (A15, A16, A17) with it’s own delay (A18).
Limits can be set for any phase extra. By setting zero value the protection is switched off.

Overfrequency protection

The protection responds to raising frequency above set threshold (A7) with it’s own delay (A8). Limit is
common for all three phases. By setting zero value the protection is switched off.

Underfrequency protection

The protection responds to fall frequency under set threshold (A9) with it’s own delay (A10). Limit is
common for all three phases. By setting zero value the protection is switched off.

Voltage assymetry protection

The protection responds to raising of the voltage difference between any two phases above set threshold
(A19) with it’s own delay (A20). By setting zero value the protection is switched off.

Vector shift supervision

The protection (A21) responds to voltage vector shift (e.g. this can be caused by jump loading generator).
No delay it is possible to adjust. By setting zero value the protection is switched off. The vector shift
supervision delay (A22) can be set from 0 s to 99.98 s (skip factor 20 ms) only at power supply switch on. It
could be used when connecting of asynchronous generators to the mains.

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Phase sequence supervision

Phase sequence supervision checks the right sequence. The angle has to be at interval (120° ± 30°)
among voltage vectors. The right phase sequence is L1→L2→L3. The LEDs L1, L2 and L3 are red flashing
at wrong phase sequence. If the voltage is too small (approx. <10% of rated voltage value) at any phase
then EEEE is displayed.

Frequency measurement

The frequency is measured in one phase. NPU selects the phase where voltage exceeds 10% of rated
value. If the voltage is not high enough sufficient in any phase then both LEDs
overfrequency/underfrequency are red flashing. The frequency cannot to be measured. In this case zero
delayed failure is evaluated.

Hint:

Previous error (red LED) indication is cleared when:

• No phase voltage is sufficient for measuring

• Phase sequence error is detected

Internal watchdog

To increase the operating safety the internal watchdog and parameters consistency checks are installed.
Flashing of LED ERR indicates NPU internal failure.
Check all adjusted parameters. If ERR is still flashing, send NPU for repair.

Output Relays

RE1 and RE4 are used mainly for proper adjusting and tests of NPU parameters. RE2 and RE3 are used
mainly for protection.

Relay RE1:

The relay RE1 opens at any new failure without delay. It closes after the time given by parameter B3.
Another failure during B3 time has no effect.

Relay RE2:

The relay RE2 opens at any failure with delay given by active protection (A8, A10, A14, A18, A20) see
table in the Chapter 6 – Displayed Quantities and Parameters. In example on the following drawing it is
Under voltage delay A18. RE2 opens immediately when Vector shift protection is activated. RE2 closes
after the time given by parameter B4. The relay doesn’t open (doesn’t indicate a new failure) until all active
failures are gone. LED ERR copies the state of RE2.

Relay RE3:

The relay RE3 opens at any failure with delay given by active protection (A8, A10, A14, A18, A20) see
table in the Chapter 6 – Displayed Quantities and Parameters. In example on the following drawing it is
Under voltage delay A18. RE3 opens immediately when Vector shift protection is activated. RE3 stays
opened until any failure is active and closes immediately when no failure is active or with delay B5 in the
case of vector shift protection.

Relay RE4:

The relay RE4 opens at any failure with delay given by active protection (A8, A10, A14, A18, A20) see
table in the Chapter 6 – Displayed Quantities and Parameters. In example on the following drawing it is
Under voltage delay A18. RE4 opens immediately when Vector shift protection is activated. RE4 closes
after the time given by parameter B3. The relay operates similar as RE2, but indicates any new failure.
This feature is available from software version 1.5 (see parameter B10 to find your software version).

Note:If there is no power supply, all relays are opened.

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Example: Evaluation of under voltage protection

t[s]

U[V]

A15

A18

<

A18

B4

L2

L1

A16

t[s]

Relay RE3

Close

Open

Relay RE2

t[s]

Close

Open

t[s]

U[V]

A15

B3

B3

<

A18

B3B3 A18

A18

B3

L2

L1

A16

t[s]

Relay RE4

Close

Open

Relay RE1

t[s]

Close

Open

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Vector Shift Protection

The vector shift protection protects synchronous generator in parallel operation in case of mains failure by
very fast opening the coupling breaker. Automatic mains reclosing for synchronous generator is very
dangerous. The mains voltage returning after 300 ms can meet the generator in asynchronous mode.
There are two main applications for vector protection:

1. parallel mode only (no island mode)

The vector protection controls the generator circuit breaker.

2. parallel and island mode

The vector protection controls the mains circuit breaker.
The NPU detects mains failure within 30 ms. The total time of disconnection is shorter than 100 ms
including disconnecting time of the circuit breaker.
The requirement for generator disconnection comes on power change of more than 15% - 20%. Slow
changes of frequency (e.g. governor commands) don’t activate the protection.

Measuring principle

When a synchronous alternator is loaded, the rotor displacement angle ϑ is build between the terminal
voltage (mains voltage)

g and the synchronous electromotive force e. Therefore a voltage difference

∆U is built between

e and g. The rotor displacement angle ϑ between stator and rotor is depending on

mechanical moving torque of the generator shaft. The mechanical shaft power is balanced with the
electrical feeder mains power and therefore the synchronous speed keeps constant.

In

a oad. The rotor
isplacement angle is decreased repeatedly and the voltage vector

Mains

U

e

U

g

Z

l

1

l

2

∆

U

Generator Mains/Load

ϑ

U

e

U

g

In parallel with the mains

c se of mains failure or auto reclosing the generator suddenly feeds a very high consumer l

g changes its direction to dg’.

Mains

U

e

U´

g

Z

l´

1

∆

U´

Generator

Load

∆ϑϑ

U

e

U

g

U´

g

A

t mains fail ure

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As shown in the timing diagram the voltage jumps to an other value and the phase position changes. This
procedure is named phase or vector surge. NPU continuously measures the cycles, starting each zero up
ward slope. The time cycle is internally compared to the quartz table reference time. In case of vector
surge the zero up ward is delayed and the device trips instantaneously. The trip angle ∆ϑ and
consequently the sensitivity of the vector surge detection is adjustable.

Measuring principle

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5. Settings

Buttons

Parameters and quantities are divided into two sets. For transfer from one set to the other press MODE
button for 5 seconds. See tables for these sets. Items (parameters and quantities) in tables are in the same
sequence as on display.
If the SET button is available (the SET button can be protected with panel fixed by two seals), parameters
can be adjusted by pressing of SET button.

For transfer between items use ↑ (up arrow) or ↓ (down arrow).

Display and LEDs

Parameters or measured quantities are displayed on four digits display.
The display switches on after pressing any button and switches off after the time given by B2. If B2 is 0,

than the display never switches off. The display switch off also aborts unfinished parameter settings.
The green LED PWR indicates power supply.
Three-color LEDs L1, L2, L3 indicate the phase that corresponds to the data on display (yellow color) or to

a failure LED (red color).
Three-color LEDs f

↑, f↓, U↑, U↓, ∆U, U, indicate failure type (red color) or data on display (yellow color).

The three-color LED ERR follows relay RE2 (red color id. RE2 is open, switches off if RE2 is closed) and
also NPU internal error (red flashing).

Notes:

If any LED shines or flashes red the failure is indicated. The failure indication has always priority to another
indications.

The LEDs L1, L2, L3, f

↑, f↓, U↑, U↓, ∆U, U, shine red immediately after failure (without delay). If RE2

relay opens LED’s starts red flashing. The LED flashing is finished by pressing any button or the time given
by B2. Failures are not indicated by red LED flashing if B2 is zero.

Parameters settings

Press the SET button and the first digit starts flashing. The flashing digit can be changed by pressing ↑(+1)
and ↓(-1) buttons. The next digit is selected by pressing MODE button.

If the required parameter value is displayed press the SET button again and the new value is stored. If a
new value is out of allowed range the NPU sets it to proximate value.

Caution: a new value is applied immediately.

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6. Displayed Quantities and Parameters

Set A:

No. Quantity

(parameter)

Front panel
signals

Characters
on display

Limits Step Unit

A1 Frequency in L1, L2, L3 Green L1,L2,L3 0,01 [Hz]
A2 Voltage L1 Green L1

1 [V]

A3 Voltage L2 Green L2

1 [V]

A4 Voltage L3 Green L3

1 [V]

A5 Max. phase asymmetry

1 [V]

A6 Max. vector shift in L1, L2, L3 Yellow L1

0,1 [°]

A7
A8

Overfrequency limit
Overfrequency delay

Green f ↑
Yellow f ↑

0;45÷65
0÷99,98

0,1
0,02

[Hz]
[s]

A9
A10

Underfrequency limit
Underfrequency delay

Green f ↓
Yellow f ↓

0;45÷65
0÷99,98

0,1
0,02

[Hz]
[s]

A11
A12
A13
A14

Overvoltage limit L1
Overvoltage limit L2
Overvoltage limit L3
Overvoltage delay

Green L1, U ↑
Green L2, U ↑
Green L3, U ↑
Yellow U ↑

0÷999
0÷999
0÷999
0÷99,98

1
1
1
0,02

[V]
[V]
[V]
[s]

A15
A16
A17
A18

Undervoltage limit L1
Undervoltage limit L2
Undervoltage limit L3
Undervoltage delay

Green L1, U ↓
Green L2, U ↓
Green L3, U ↓
Yellow U ↓

0÷999
0÷999
0÷999
0÷99,98

1
1
1
0,02

[V]
[V]
[V]
[s]

A19
A20

Voltage asymmetry limit
Asymmetry delay

Green ∆U
Yellow ∆U

0÷999
0÷99,98

1
0,02

[V]
[s]

A21
A22

Vector shift limit
Vector shift evaluation delay on

voltage connection

Green U
Yellow U

0÷50
0÷99,98

1
0,02

[°]
[s]

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Default setting

No. Quantity (parameter) Rated voltage
100V 230V 400V 480V
A1 Frequency in L1, L2, L3
A2 Voltage L1
A3 Voltage L2
A4 Voltage L3
A5 Max. phase asymmetry
A6 Max. vector shift in L1, L2, L3
A7
A8

Overfrequency limit
Overfrequency delay

52 (62) Hz

2,5 s

52 (62)Hz

2,5 s

52 (62) Hz

2,5 s

52 (62) Hz

2,5 s
A9
A10

Underfrequency limit
Underfrequency delay

48 (58) Hz

2,5 s

48 (58) Hz

2,5 s

48 (58) Hz

2,5 s

48 (58) Hz

2,5 s
A11
A12
A13
A14

Overvoltage limit L1
Overvoltage limit L2
Overvoltage limit L3
Overvoltage delay

110 V
110 V
110 V

2,5 s

253 V
253 V
253 V

2,5 s

440 V
440 V
440 V

2,5 s

528 V
528 V
528 V

2,5 s
A15
A16
A17
A18

Undervoltage limit L1
Undervoltage limit L2
Undervoltage limit L3
Undervoltage delay

85 V
85 V
85 V

2,5 s

196 V
196 V
196 V

2,5 s

340 V
340 V
340 V

2,5 s

432 V
432 V
432 V

2,5 s
A19
A20

Voltage asymmetry limit
Asymmetry delay

15 V

2,5 s

30 V
2,5 s

60 V
2,5 s

60 V

2,5 s
A21
A22

Vector shift limit
Vector shift evaluation delay on
voltage connection

20

2,5 s

20

2,5 s

20

2,5 s

20

2,5 s

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Set B:

No.

Quantity

(parameter)

Front panel

signals

Characters

on display

Limits Step Unit

B1

Failure time signaling
(red LED’s flashing time)

Flashing green

L1,L2

0÷9999

1 [min]

B2

Display switch off time

Flashing green

L1, L3

0÷9999

1 [min]

B3

Relay RE1, RE4 switch off time Flash. yellow

L1, L2

0÷99,98

0,02 [s]

B4

Relay RE2 switch off time Flash. yellow

L1, L3

0÷99,98

0,02 [s]

B5

Relay RE3 switch off time
for vector shift protection

Flash. yellow

Uá

0÷99,98

0,02 [s]

B6

Max. vector shift in L1, L2, L3 (from
manual reset)

Yellow

L1, L2, L3

0÷0

[°]

B7

Angle between L1 and L2 Yellow L1, L2

1 [°]

B8

Angle between L2 and L3 Yellow L2, L3

1 [°]

B9

Display and LED’s brightness

0÷9

1

B10

Software release

B11

Display and LED’s test All LEDs

yellow

(no failure)

ERR red

Time delays are set with step 0.02 s (without relay drop out time - c. 0.01 s has to be added).
The Max. vector shift (A6) is the highest measured value between data recovery on display. The Max.
vector shift (B6) is the highest measured value between manual resets. This could be used for a long-term
monitoring of the grid’s vector shifts. Reset of B6: Set zero like in the other parameters.
Setting zero bold typed parameters switches off the appropriate protection.
Exception: B2 set to zero makes the display shining continuously.

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Default setting

No. Quantity (parameter) Default
B1 Failure time signaling

(red LED’s flashing time)

2880 min

B2 Display switch off time 10 min
B3 Relay RE1, RE4 switch off time 5 s
B4 Relay RE2 switch off time 5 s
B5 Relay RE3 switch off time

for vector shift protection

2,5 s

B6 Max. vector shift in L1, L2, L3 (from

manual reset)
B7 Angle between L1 and L2
B8 Angle between L2 and L3
B9 Display and LED’s brightness 7
B10 Software release
B11 Display and LED’s test

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7. Order codes

NPU - XXX / YYY / ZZZ

XXX functions: FU / FUV
YYY measurement range: 100 / 230 / 400 / 480 VAC
ZZZ power supply range: 230VAC / 24VDC

Order code

Frequency

protection

Voltage

protection

Voltage

asymmetry

protection

Vector shift

supervision

Rated

voltage

Power

supply

voltage

NPU-FU/100/230VAC
NPU-FU/100/24VDC

YES

Yes

Yes No 100V

230VAC

24VDC
NPU-FU/230/230VAC
NPU-FU/230/24VDC

Yes Yes

Yes No 230V

230VAC

24VDC
NPU-FU/400/230VAC
NPU-FU/400/24VDC

Yes Yes

Yes No 400V

230VAC

24VDC
NPU-FU/480/230VAC
NPU-FU/480/24VDC

Yes Yes

Yes No 480V

230VAC

24VDC
NPU-FUV/100/230VAC
NPU-FUV/100/24VDC

Yes Yes

Yes Yes 100V

230VAC

24VDC
NPU-FUV/230/230VAC
NPU-FUV/230/24VDC

Yes Yes

Yes Yes 230V

230VAC

24VDC
NPU-FUV/400/230VAC
NPU-FUV/400/24VDC

Yes Yes

Yes Yes 480V

230VAC

24VDC
NPU-FUV/480/230VAC
NPU-FUV/480/24VDC

Yes Yes

Yes Yes 480V

230VAC

24VDC