esponsible for its content.
Powerbrake Powerbrake
PBC Range DC Injection Critical Brakes
Powerbrake PBC is a range of self-contained D.C. Injection Critical
Brakes for 400V three-phase motors from 3.0 to 75 kW.
Powerbrake PBC is designed to be used in conjunction with a
conventional direct-on-line or star-delta motor starter for normal
starting and stopping functions. In the event that a pair of trip
contacts is opened, Powerbrake PBC will provide rapid braking
while minimising the maintenance associated with mechanical
brakes.
Powerbrake PBC incorporates a line contactor to control the three-
phase power to the motor starter. An electronic control unit and
semiconductor switching devices provide an adjustable D.C.
injection braking current to the motor via the internal braking
contactor, whenever the trip contacts open. During braking the line
contactor automatically removes the normal three-phase supply
from the starter. A reset button must be operated before the motor
can be re-started.
Note that injection braking cannot operate in the event of supply
failure. A risk assessment should therefore be undertaken to
determine whether the application requires additional backup. D.C.
injection brakes do not lock the motor in the rest position after the
selected braking time has elapsed.
Order references
PBC3-XXX
3kW (4hp) 400V 7A FLC maximum
PBC5-XXX
5.5kW (7.5hp) 400V 12A FLC maximum
PBC7-XXX
7.5kW (10hp) 400V 16A FLC maximum
PBC11-XXX
11kW (15hp) 400V 23A FLC maximum
PBC15-XXX
15kW (20hp) 400V 32A FLC maximum
PBC22-XXX
22kW (30hp) 400V 45A FLC maximum
PBC30-XXX
30kW (40hp) 400V 63A FLC maximum
PBC37-XXX
37kW (50hp) 400V 75A FLC maximum
PBC45-XXX
45kW (60hp) 400V 86A FLC maximum
PBC55-XXX
55kW (75hp) 400V 105A FLC maximum
PBC75-XXX
75kW (100hp) 400V 136A FLC maximum
N.B. Replace XXX with 110 for 110V control supply
230 for 230V
400 for 400V
Technical specification
Supply
380...415V
+10% - 15%
voltage:
50-60Hz
___________________________________________________
Current rating: As shown under Order References above.
All units:
Braking current 2x motor rated FLC max.
___________________________________________________
Internal adjustments:
Braking time 0.1-15s
Braking torque (current) 10-100% rated max
___________________________________________________
Internal indicators:
Green - Power On
Amber - Braking
Red - Fault*
*Refer to diagram on top of DCB5A/DCBUA braking module
___________________________________________________
Fault Protection:
Motor temperature high / P1-P2 link missing
1
Heatsink above rated temperature
2
Thyristor fuse/supply failure
Thyristor failure
Disconnected brake time potentiometer
3
1
Applies only to motors fitted with PTC thermistors to BS4999
2
Excessive braking current or frequency of braking
3
L
ink T1 T2 missing
Panel hardware: Fault indicator lamp (amber)
RESET button
___________________________________________________
Enclosure rating: IP55
___________________________________________________
Humidity: Maximum 95%, non-condensing
___________________________________________________
Ambient temperature: -10
°
C to+40
°
C
___________________________________________________
Terminal cable capacity: 3kW - 11kW 4mm
2
15kW - 22kW 10mm
2
37kW - 45kW 35mm
2
55kW - 75kW Bolted lug
___________________________________________________
Weight: 3kW & 5.5kW 5.3kG
7.5kW, 11kW & 15kW 7.0kG
22kW & 30kW 11.0kG
37kW & 45kW
55Kw & 75kW
Terminal functions
1
3 3-phase supply voltage
5
2
4 3-phase out to motor starter
6
U

D.C. braking current output to motor
V
E1
Normally Closed trip contact
E2
P1
PTC motor thermistors to BS 4999
4
(or link)
P2
4

Must trip at T
R
= 2000 4000 ohms (hot)
Must reset at T
R
= less than 750 ohms (cold)
Applications information
The operating sequence is shown on the graph overleaf. The d.c.
braking current is injected into two motor terminals after the three-
phase supply has been disconnected. The magnitude of the braking
current and braking torque is dependent on:
a. The stator winding resistance of the motor and
b. The setting of the torque control (adjustable 10 100%)
In practice the braking current should be adjusted to be no more
than twice the motor rated current, i.e. I
B


2I
N
. Higher currents can
cause saturation of the stator windings and lead to overheating, with
no corresponding increase in braking torque.
The braking time is dependent on motor and load characteristics, as
well as braking current, in accordance with the following
approximate formula:
0.1 x I
LR2
x J x n
t
B
= seconds
I
B2
x T
LR
where t
B
is the braking time
I
LR
is locked rotor current in A
I
B
is braking current in A
T
LR
is locked rotor torque (Nm)
J is the total moment of inertia of motor and load in kgm
2
N is the motor speed in rpm
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Technical Specification

English
Issue 3
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} Technical Specification
English

Issue 3
ENTRELEC MTE LIMITED Stephenson Road Leigh-on-Sea Essex SS9 5LS
Telephone +44(0) 1702 421124 Fax +44(0) 1702 510453
06 012261/3E/302
Operation
(See Typical Wiring Diagrams, opposite).
Check wiring carefully. Before switching on, check that the
TORQUE and TIME setting potentiometers on the DCB5A or
DCBUA control module within the PBC unit are set to minimum
(counter-clockwise). If possible, a moving iron ammeter or true-
RMS clamp meter should be available to measure the d.c. injection
current in the cable leading from terminal U on the PBC unit to the
motor.
Turn on the supply to the PBC unit. Press the START button on the
motor starter. The motor should not start. Press the RESET button
on the PBC unit. The motor should start and stop normally. With the
motor running, open the trip contacts. The line contactor in the PBC
should de-energise, stopping the motor and disabling the starter.
There will be very little braking effect at this stage. It should not be
possible to restart the motor until the RESET button is pressed. The
TORQUE and TIME controls should be advanced about ¼ turn
clockwise. Restart the motor. When the trip contacts are next
opened the BRAKE LED on the DCB5A/DCBUA module will illuminate
for about 3s and the motor should stop more quickly than before.
If the amber FAULT light illuminates it is possible that the motor is
too hot (if thermistors are fitted) or that terminals P1 & P2 have
been left unconnected. On units of 7.5kW or greater, the heatsink in
the PBC may be too hot as a result of excessive braking. Thyristor
fault or fuse failure will also be indicated. The red fault LED on the
DCB5A/DCBUA shows continuously or flashes at differing rates
depending on the type of fault. A key to fault LED indications is
printed on the DCB5A/DCBU/A top data panel.
The process of adjustment may be repeated until the required
stopping performance is achieved. This may be a smooth stop over
several seconds or a short sharp braking action. Avoid violent
braking which could damage the machine or the PBC unit. The d.c.
braking current is only measurable while the BRAKE LED is on and
must not exceed 2 x rated FLC for the motor. If a suitable ammeter
is unavailable, do not advance the TORQUE control beyond its
midpoint setting. The TIME control should be set so that the BRAKE
LED goes out just as the motor comes to rest. Excessive braking
time and/or current will simply cause overheating of both motor and
the PBC unit. Do not exceed 12 stops per hour, evenly spaced. Data
is available for higher stopping rates but these should not generally be
necessary in applications for which the PBC unit is intended.
Operating sequence
Dimensions (mm)
W H D
3/5.5kW 310 x 200 x 142
7.5/11/15kW 400 x 200 x 142
22/30kW 260 x 460 x 155
37/45kW 400 x 450 x 166
55/75kW 500 x 800 x 253
Typical wiring diagram (DOL motor)
Typical wiring diagram (Star-delta motor)
*N.B. These terminals are not present on units having 400V control
voltage because the control supply is internally wired.
Installation
The supply must have an isolator as shown. Motor rated fuses and
overloads should be used in the normal way. A Bussmann high
speed semiconductor fuse is fitted inside the PBC unit to protect the
braking thyristor, as follows:
3kW & 5.5kW
type 63FE
7.5kW, 11Kw & 15kW
type 90FE
22kW
type 100FE
30kW
type 140FEE
37kW & 45kW
type 180FM
55kW & 75kW
type 225FM
N.B: Two control circuit fuses are also fitted internally. These are
32x6.3mm, Belling type L693, rated at 5A. Under normal
circumstances these should not require replacement.
WARNING:
Semiconductor devices transmit leakage current. Before
installing or attempting adjustments or maintenance on PBC
unit, starter or motor, the supply must be disconnected.
Council of European Communities Directives:
The products in this publication conform to relevant EEC Directives and EN Standards. Installation and use of such products must
be carried out by competent, properly trained personn