MEC 2 MICROPROCESSOR ENGINE/GENERATOR CONTROLLER
PM056 Rev 6 05/10/15
Thomson Technology
8
2.6. AC CURRENT INPUT
Current transformers (CT’s) must be used to supply the MEC 2 current inputs. CT
polarity is not critical for correct circuit operation.
Note:
The CT secondary common
conductors must be externally grounded for correct operation. CT’s must be rated for a
minimum of 1.5VA output at the specified accuracy.
CAUTION!!!
When installing or performing any service work on CT circuits, always de-
energize the system before proceeding with any work. Never open circuit
an energized CT as extreme high voltages may result which may cause
serious injury or death.
2.7. OUTPUTS
All outputs from the MEC 2 are relay driven contacts. Relay contacts have a
10A/240VAC resistive (3 Amp inductive 0.4pf), 8A/24Vdc rating and are isolated Form A
& Form C types. Interposing relays are recommended between the MEC 2 outputs and
end devices to prevent internal damage due to possible excessive current draw and/or
damage should an external fault occur.
Note:
These outputs will require external over
current protection (Maximum 10 Amp).
The use of AC or DC operated solenoids or relays in control systems can sometimes
cause high voltage spikes on the DC power supply, which may cause electronic devices
to fail. Transient suppression devices are recommended for all inductive devices
sharing wiring or if physically located near engine/generator control panels. For DC
operated relays or solenoids, use a suitably rated counter EMF Diode (or commonly
known as “freewheeling” diode). For AC operated relays or solenoids, use a suitably
rated metal oxide varistor (MOV) or capacitor/resistor suppressor.
2.8. EXTERNAL PANEL CONTROL WIRING
As a minimum, all control wiring shall conform to the local regulatory authority on
electrical installations. Specific wire sizes for typical circuits (of distances up to 100ft
(30m)
) are as follows:
2.8.1. Battery Control Power
#14 AWG (2.5mm
2
)
2.8.2. Engine Alarm/Shutdown Contacts
#16 AWG (1.5mm
2
)
2.8.3. Remote Start Contact for Transfer Switch #14 AWG (2.5mm
2
)
Summary of Contents for MEC 2
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