MER-MAN-14V01 (1002)
Copyright © 2014 Defi ne Instruments
13
noise typically found in circumstances
when signal cable is laid on top of noisy
switching power cables. Of course in
this case you are better off to keep sepa-
rate signal and power lines.
C
Laying cable on earthed cable trays can
also help reduce noise seen by the me-
ter. This is particularly useful if there are
long cable runs, or the unit is close to ra-
diating sources such as two way radios.
D
The relay outputs of the Merlin have
built in MOVs to help reduce EMI when
switching inductive loads. EMI can fur-
ther be reduced at the load by adding
snubbers for AC signals or a fl yback di-
ode for DC coils.
5.3 - Back panel
The back panel of the Merlin may have up to fi ve screw terminals (A, B, C, E & F) and one USB
programming jack (D). Ports C, E and F are installed on the R2A model only.
A
Sensor input
(Pins 1–6, See Section 6)
B
Power supply
(Pins 7–8, See 5.4)
C
Analogue output
(Pins 9–10, See 5.6)
D
USB programming jack
(See Section 4)
E User
input
(Pins 11–12, See 5.8)
F
Relay outputs
(Pins 13–16, See 5.7)
5.4 - Power supply
See 5.3B, pins 7–8
The Merlin features a wide range
Power Supply
that suits both AC
mains and 24V DC applications. The Merlin uses a full bridge rectifi er, so
it is not sensitive to polarity
for DC power inputs.
CAUTION
Risk of electric shock.
AC power supplied to the meter must be protected by a 10A cir-
cuit breaker. DC power supplied to the meter must be protected
by a 1A, 250V fuse.
