9
1.
DESCRIPTION OF EQUIPMENT
The PCU1 mk2 series are medium powered primary current injection systems offering output
currents up to 5000A. The system consists of a separate control unit containing all metering
and control functions and a loading unit that provides the high current output. The PCU1-LT
mk2 and PCU1-SP mk2 are ideally suited to primary current injection, stability testing and
circuit breaker testing. In addition, the SP version offers direct-reading CT ratio and polarity
tests and a 100A secondary injection output.
All references to the PCU1-SP and PCU1-LT in this manual refer to the PCU1-SP mk2 and
PCU1-LT mk2.
Three loading units are available, delivering a maximum output current of 200A, 2000A or
5000A. Each loading unit has two or three output taps to allow for a wide range of load
impedances. For example, the NLU5000 may be configured to either give a maximum current
of 5000A on the 2.3V range, 2500A on the 4.6V range or 1250A on the 9.2V range.
The control units are rated at 11.5kVA. All metering is digital, and a memory facility is
provided to hold the current reading when the output trips or is switched off. The current is
thyristor controlled and is automatically switched off when the device under test trips.
The PCU1 systems have a high accuracy timing system, allowing timing tests to be carried
out to a resolution of 1ms. Selection for normally open or normally closed contacts is
automatic, and the status of the contacts is shown on the front panel.
Timing modes are available to test under and over current devices, re-closers, under and over
voltage devices, current trips and circuit breakers. A full range of high current output leads
are available to complement the system in a range of lengths.
WARNING
The PCU1 and associated loading units are designed to be used on ‘dead’
systems (i.e. no externally supplied voltages are present on the test object).
Under no circumstances connect a PCU1 to a live system. Always check that
the power to the device under test is off and the circuit is isolated and earthed
before making any connections.
