P&B MPC2000+ Technical Manual page 11

MPC2000+ Technical Manual
5. MPC2000+ Measured Inputs
5.1. Power Supply (Live-4, Neutral-5, Earth-7)
The MPC2000+ requires 240 or 110v A.C. to supply the unit and provides the selected A.C. voltage to all external
inputs. The voltage used is set via a switch situated on the rear cover of the unit.
The MPC2000+ monitors the power supply assumed to be derived from the primary side of the contactor within the
starter cubicle or from the MCC busbars to provide an Undervoltage Dip Restart facility. When enabled in the System
Settings page the MPC2000+ monitors the supply and in the event of a failure will maintain the start signal to the
motor for upto 200 msec, beyond 200 msec the unit will trip the motor and should the Power supply be restored within
4 seconds the unit will restart the motor after a time delay set in the Undervoltage Settings page. Should the voltage
not be restored within 4 secs the motor will not be automatically restarted
5.2. VT Inputs (L1-16, L2-18, L3-20, N-17,19,21-if used)
The MPC2000+ monitors single or three phase voltage, which can be directly connected for voltages upto 660v and
via a suitable voltage transformer for system voltages above 660v . In order that the MPC2000+ can measure and
display actual volts, the system volts and VT primary and secondary volts must be set in the 'System Settings' page.
If single phase voltage reference only is available this is connected to L1 and N with L1,L2,L3 commoned. The
'System Voltage ' setting in the 'System Settings' page must then be set to 1.732 x the line voltage. In addition the
Phase Sequence and Phase Loss protective functions must be disabled
If there is no 3 phase reference the Power & Power Factor monitoring of the unit will not function.
5.3. Current Sensor Inputs (10,11,12,13,14,15)
To allow MCC manufacturers to use the smallest size compartments P&B have developed a highly accurate dedicated
Current Sensor. The unit is a compact 3 phase resin encapsulated device. The Current Sensor comes complete with
flying leads and connectors to plug directly into the associated MPC2000+ terminal block.
5.4. Earth Fault CT Inputs (8,9)
The MPC2000+ can detect earth faults using either a separate core balance CT or by connecting the 3 phase CT's
reference residually. A converter is available for 1A CT outputs as an optional extra. Please note that the Earth Fault
value is not displayed on the MPC2000+ till it reaches a value greater than 50% of the lowest Earth Fault Trip value.
5.5. Temperature Inputs (23,24,25;26,27,28;29,30,31)
Thermistors of either positive or negative temperature coefficients can be directly connected to the MPC2000+ by
selecting either PTC or NTC in the default menu. The alarm and tripping range can be adjusted between 100 ohms
and 30,000 ohms.
RTD's can also be directly connected to the MPC2000+ and selecting between the two inputs is via the front plate
keypad. As the resistance of RTD's is relatively low, the MPC2000+ use a three wire measurement system for each
RTD, the third wire is required to compensate for the wire resistance. The alarm and tripping range of the RTD's can
be adjusted between 100 ohms and 240 ohms. Default setting is for RTD inputs.
As standard the MPC2000+ is internally set for Thermistor temperature inputs. If RTD inputs are to be used this
should be stated at the time of order placement, however the unit can be changed on site, instructions are available
form P&B Engineering upon request.
5.6. Power.
The Power applied to a motor is displayed on the MPC2000+ and is calculated from the Current and Voltage inputs to
the relay. Please note that due to this calculation the Power and Power Factor is less accurate for Motors with a CT
Primary of less than 10 Amps.
P&B Engineering ISSUE 7 28/9/99 Page 7