RP81, 3-phase phase angle relay0 pages

C-mac

®

Load guard RP81

Load guard for 3-phase motors
Power factor metering (cos j)
Adjustable time delay 0-20 sek. at motor start
Selectable release of relay at max. or min. load
1-pole relay output 8A / 250 VAC
Produced in accordance with
and EMC regulations
C-mac® module type RP81 is used for load monitoring of
3-phase motors, as the phase angle (cos j) between motor
current and -voltage changes in proportion to the mechanical load of the motor.
You will see the biggest change in phase angle, if the motor is loaded between 0 and 60% of nominal load, which
makes the RP81 suitable for monitoring of V-belts,
pumps running dry, etc. (see page 6-6).
RP81 can be connected directly to motors with nominal
current up to 6 A. If the current is bigger, you use a standard current transformer.
The unit is supplied with an adjustable start-up delay,
which keeps the output relay activated independant of the
power consumption, when the motor is starting.
By connection of pins 7 and 2 you can select if the relay
releases at over- or underload.

Start-up:

Relay function:

When the supply voltage is connected,
the output relay activates, and the
start-delay will start, independant of
the selected relay function.
pins 2-7.
If pin 2 is not connected, the output relay
releases immediatly, if the power factor
exceeds the set level, provided that the
set start-delay has run out.
If pin 2 is connected to pin 7, the relay
releases, if the power factor is lower than
the set level, and the timer has run out.

Functional diagram:
supply

Technical data:
Supply voltage:

Supply frequency:
Power consumption:
Operation temp.:
Humidity:
Monitoring current:

Internal shunt:
Hysteresis:
Adjustments:
Start delay:
Level:
Accuracy, scale:
Start delay:
Level:
Indications:
Green LED:
Red LED:

3 x 230 V +/- 10%
3 x 400 V +/- 10%
3 x 415 V +/- 10%
40-70 Hz
2,5 VA
-20°C to +60°C
0 - 90% RH, non-condensing
min. 0,5 A, max. 6 A
At bigger currents use a
standard current transformer..
33 mW. At max. current 6 A
the voltage across the shunt is 0,2 V
5% of adjusted level.

setpoint
hysteresis
load
relay, ex. 1
relay, ex. 2

t

t

t

t = selected start-up delay
ex. 1: overload, pins 2-7 open
ex. 2: underload, pins 2-7 connected

Potentiometer, 0-20 sec.
Potentiometer, cos.j 0-0,9
20%
5%
Supply voltage connected
Relay activated

Comadan
Produktion a/s

6-1