S&S Northern Merlin PM2 Operational manual

Merlin PM2 Double Current Monitor Product Data Sheet
S&S Northern Ltd 1
Gas Safety Products
Merlin PM2 Double Current Monitor
Installation, operating and maintenance
25/11/2015

Merlin PM2 Double Current Monitor Product Data Sheet
S&S Northern Ltd 2
Table of contents
1General information ..........................................................................................3
2Installation .........................................................................................................3
2.1 Panel Mounting.
2.2 Power Supply..................................................................................................................3
2.3 Current Monitor...............................................................................................................3
3Operation Instructions......................................................................................3
3.1 The PM2 current monitor ................................................................................................3
PM2 Wiring Diagram.................................................................................................4

Merlin PM2 Double Current Monitor Product Data Sheet
S&S Northern Ltd 3
1 General information
The Merlin PM2 Current Monitor is a dual fan current monitor and is to be used in conjunction
with the Merlin 1500S, CT1750 and 2000S System; it can be used as an alternative to an air
pressure differential switch.
The PM2 Current Monitor checks for a current running between the fan speed controller and
the fan and sends a signal to the Merlin gas interlock system dependant on whether or not the
fan is in operation.
It is recommended that the user reads this guide before using the system. Please do NOT
attempt to operate the unit until the contents of this document have been read and are
thoroughly understood.
2 Installation
2.1 Panel Mounting. The control panel is designed for surface mounting using 4 mounting screws.
Removing the cover on the panel gives access to the circuit board.
2.2 Power Supply. A 12vdc electrical supply should be supplied to the PM2 using the ‘12VDC’
terminal inside the Merlin gas interlock system and connected to the terminal marked ‘+ -
POWER’.
2.3 Current Monitor. On the base of the circuit board there are two sets of terminal marked “IN
OUT LIVE”. The live feed from the fan controller should be taken to the Merlin PM2 and
connected of the terminals. On the top of the circuit board there is a potentiometer marked
“SENS 1” on the left side and marked “SENS 2” on the right side of the panel. The fan should
be run at minimum speed and the potentiometer turned clockwise until the green LED on
the PCB, located in the middle of the panel, lights up. This indicates the panel has seen the
electrical current going to the fan. If a second fan is connected this procedure should then
be repeated on the other potentiometer. The panels are sent from the factory with links in the
terminal connections marked “Fan PD Switches supp fan & Extr fan” on the Merlin gas
interlock system. These terminals are low voltage, mains supply must NOT be introduced to
these terminals. If both supply fans and extract fans are being monitored both theses links
should be remove and a low voltage connection should be supplied to the terminals marked
‘TO CTX PANEL’ on the Merlin PM2 panel. If only one fan is being monitored the relevant link
should be taken out of the terminal connection. .
Note: all low voltage connections should be made using a screened cable to
avoid electrical interference.
3 Operation Instructions
3.1 The PM2 current monitor requires a 12vdc power supply. (This is normally provided from the
main Merlin system which it is used in conjunction with).

Merlin PM2 Double Current Monitor Product Data Sheet
S&S Northern Ltd 4
PM2 Wiring Diagram
1. Power Input from Merlin Panel, 12VDC.
2. Connection to Merlin 1500S or 2000S Air PD terminals. LOW VOLTAGE
3. Supply Fan current monitor, MAX 20AMPS
4. Potentiometers.
5. LED Lights.
Please note, Mains wires and low voltage wires should
not be run in the same conduit as per the LOW
VOLTAGE DIRECTIVE

Merlin PM2 Double Current Monitor Product Data Sheet
S&S Northern Ltd 5
CONTACT US:
S&S Northern Head Office
Tel: [phone]
Fax: [phone]
www.snsnorthern.com
[e-mail]
South East Division
Tel: [phone]
Fax: [phone]
[e-mail]
Rev
Date
Author
Description
03
25.11.15
S&S Northern
CD + BT
Merlin PM2 Product Data Sheet –Third issue
S&S Northern is the owner of this document and reserves all rights of modification without prior notice.