Powtier Controls 505MST User manual

Multi-Stage Thermostat
505MST/M
for
MK3 HST
Instruction Manual
Contents
Introduction...........................................................................................2
System control.......................................................................................2
Temperature setpoints...........................................................................2
Lower level damper solenoid................................................................5
Sensor....................................................................................................6
Installation.............................................................................................7
Test and calibration...............................................................................8
System layout diagram..........................................................................9
System connection diagram.................................................................10
Internal board layout diagram..............................................................11
Sensor dimensional drawing...............................................................12
Technical Specification.......................................................................13
Ordering information...........................................................................15
Supplier information...........................................................................15
Copyright (C) 1998 Powtier Controls Limited
This document contains proprietary information which is protected by copyright. All rights reserved. This document or parts thereof may not
be reproduced in any form without written permission of the publishers.
The information in this document is subject to change without notice and should not be construed as a commitment by Powtier Controls
Limited. Powtier Controls Limited shall not be liable for errors contained herein or for incidental or consequential damages in connection
with the furnishing, performance or use of this material.

Powtier Controls Limited 505MST Thermostat
Instruction Manual
Introduction
The 505MST/M is an electronic five-stage thermostat which caters for the heating and cooling
requirements on the MK3 HST trailers, replacing a electromechanical device.
The 505MST/M is an intelligent thermostat unit. Its design is based on the latest micro-
controller chip technology.
Special features of the 505MST/M include: the 'Winter/Summer' temperature compensation,
prevention of temperature overshoot and undershoot, selectable setpoint temperature
switchings and time-delay.
System control
The 505MST/M Electronic Thermostat consists of two sensor inputs; one sensor monitors the
saloon temperature and the second sensor monitors the ambient (outside air) temperature.
The Thermostat has five relay outputs. These are primarily used for the switching of:
1. Heater 1
2. Heater 2
3. Heater 3
4. Low level damper solenoid
5. Cooling
The relay outputs are designed to drive externally connected contactors.
Temperature setpoints
Table A, B and C give four possible manually selectable saloon temperature setpoints for the
winter period.
Note 1: Under Table A, the winter and summer periods use the same temperature
switching points.
Note 2: Under Table B and C, the settings are for the winter periods.
Note 3: During the summer period, the 505MST/M automatically use Table A settings.
However, during the winter period, there are three possible temperature settings,
depending on the setpoint switch (see Table S2).
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Instruction Manual
Table A, Output switching (SW3=0, SW4=0)
Output State Temperature Description
H3 OFF 18.5°C 16KW ON
ON 17.5°C 24KW ON
H2 OFF 20.5°C 8KW ON
ON 19.5°C 16KW ON
H1 OFF 21.5°C Heat OFF
ON 20.5°C 8KW ON
LLDS ON 21.5°C LLDS energised (no timer)
TD then OFF 20.5°C After timer-delay (TD), LLDS de-energised
C ON 22.5°C Cooling ON
OFF 21.5°C Cooling OFF
Table B, Output switching (SW3=0, SW4=1)
Output State Temperature Description
H3 OFF 19.5°C 16KW ON
ON 18.5°C 24KW ON
H2 OFF 20.5°C 8KW ON
ON 19.5°C 16KW ON
H1 OFF 22.5°C Heat OFF
ON 21.5°C 8KW ON
LLDS ON 22.5°C LLDS energised (no timer)
TD then OFF 21.5°C After timer-delay (TD), LLDS de-energised
C ON 23.5°C Cooling ON
OFF 22.5°C Cooling OFF
Table C, Output switching (SW3=1, SW4=0)
Output State Temperature Description
H3 OFF 20.5°C 16KW ON
ON 19.5°C 24KW ON
H2 OFF 22.5°C 8KW ON
ON 21.5°C 16KW ON
H1 OFF 23.5°C Heat OFF
ON 22.5°C 8KW ON
LLDS ON 23.5°C LLDS energised (no timer)
TD then OFF 22.5°C After timer-delay (TD), LLDS de-energised
C ON 24.5°C Cooling ON
OFF 23.5°C Cooling OFF
H3 - Heater 3; H2 - Heater 2; H1 - Heater 1; C- Cool; LLDS - Low level damper solenoid.
Automatic winter/summer switching
An ambient sensor is fitted inside the thermostat unit and must be exposed to the ambient
temperature.
There are three possible winter/summer switching temperature, the selections are made using
the (SW1 and SW2) of the 4-way (dual-in-line) switch. See Table S1.
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Instruction Manual
For example, using Table S1 (SW1=0, SW2=1). During the rising ambient temperature and at
15°C, the unit automatically switches to summer period; during a falling temperature and at
12°C, the unit automatically switches to winter period.
Table S1, Winter/summer setpoint switch
SW1
SW2
Winter
Summer
0
0
<9°C
>12°C
0
1
<12°C
>15°C
1
0
<15°C
>18°C
1
1
<12°C
>15°C(default value)
Note that the SW1 and SW2 setpoint switches will not be provided in the final production
units, as the temperature switching would be decided after the trial period.
Winter/summer LED indication
A green Led becomes illuminated to indicate a summer ambient temperature. This LED is
visible from the outside of the MST505/M unit, via the clear perplex window.
With reference to Table S1, the green LED becomes illuminated when the ambient
temperature reaches 12°C or 15°C or 18°C during the rising temperature.
The LED is off when the temperature falls below 9°C or 12°C or 15°C.
The LED is useful during testing and commissioning, as it is the only indication for ambient
temperature. For example, if the LED is off, it is in the winter switching condition and that
Table B is referred to (if SW3=0, SW4=1); if the green LED is on, Table A is referred to
(refer to Note 3 of clause 3).
Temperature setpoint switch
A PCB mounted, SW3 and SW4 parts of the 4-way (dual in line) switch is used for the
selections of temperature settings. There are three possible temperature settings, as shown
under Table S2.
Note that during the summer period (green LED on), the unit automatically refers to Table A
temperature settings.
Table S2, Temperature setpoint switch
SW3
SW4
Description
0
0
Table A
0
1
Table B
1
0
Table C
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Instruction Manual
Lower level damper solenoid (LLDS)
The LLDS is energised to close the damper whilst in the "Vent" or "Cooling" stages.
The LLDS is energised when the VENT LED is ON. LLDS is de-energised when the VENT
LED is OFF.
During rising temperature, when heater 1 (H1) is switched OFF, the LLDS is immediately
energised.
LLDS time delay
During falling temperature, from "Vent on", to "Heater 1 on"; there is a time delay before the
LLDS could be de-energised, that is "Vent off". If however, in the event that the saloon
temperature rises again above the "H1 off", the timer would be reset to zero and that the LLDS
would remain energised.
The time delay is adjustable between 30 to 158 seconds using a 25-turn encapsulated
potentiometer. Clockwise adjustment increases the time delay.
The LLDS time delay potentiometer is located on the top left-hand corner of the PCB, easily
identified with the following legions on the PCB (please refer to Internal board layout diagram
for detail):
PT
FULLY CW - 120 SEC
FULLY CCW - 30 SEC
Note: CW indicates ClockWise. CCW indicates Counter ClockWise.
IMPORTANT
It is important to note that the time delay PT potentiometer is the only potentiometer which is
user adjustable.
DO NOT adjust the other three potentiometers, PA, PS and PZ - these are used for factory
calibration adjustments.
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Instruction Manual
Sensor
There are two temperature sensors in each 505MST; saloon sensor and ambient sensor.
Saloon sensor
The saloon sensor is a platinum resistance thermometer PT100 to BS1904 class B, with error
not greater than +/-0.3 ° C, 2-wire connection.
A two core, screened cable is used; type BR Cat.No: 6/146700; the screen of the cable is
connected to the SCREEN terminal provided inside the unit. The distance between the sensor
and the thermostat unit must be less than 5 metres.
The saloon sensor is located outside the 505MST/M unit and is connected to the inside of the
unit via a common cable gland.
Please refer to the Sensor dimensional drawing for detail.
Testing of saloon sensor
To test the saloon sensor, it is necessary to use the TC1000 portable test-jig, by simply plug in
the Litton plug of the TC1000 test-jig into the 505MST/M diagnostic socket. If the saloon
sensor is healthy, it would indicate a correct temperature on the TC1000 LCD display.
If the saloon connection to the 505MST/M unit is broken, the TC1000 would show a "1bbb"
reading (b: blank display).
Ambient sensor
The ambient sensor is a Negative Temperature Coefficient sensor (NTC), type 10KA31; it has
a temperature accuracy of +/-0.2°C.
The ambient sensor is fitted inside the 505MST/M, for this reason the 505MST/M thermostat
assembly must be located, so that it is exposed to the ambient temperature.
The ambient sensor is located at the top, left-hand side of the PCB, clearly identified with the
legion "NTC".
Testing of ambient sensor
The ambient sensor works in association with the green LED; during the summer period, the
green LED is on.
During testing, the ambient sensor could be fooled into winter by spraying it with an Aerosol
Freezer (RS 497-274), this would result the green LED to turn off.
During the winter period (green LED off); if a warm finger touches the ambient sensor (NTC),
it would turn the 505MST/M into summer period, as indicated by the green LED becoming
on.
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Powtier Controls Limited 505MST Thermostat
Instruction Manual
Installation
Please refer to System layout diagram for details.
Fixings
The 505MST/M thermostat unit could be mounted in any orientation by 4xM6 fixing holes.
Electrical connection
Please refer to System connection diagram for details.
Supply connection
The 505MST/M thermostat is powered by a 110Vdc and connection is made to the M4 stud
terminal marked "0" and "110".
The `0' volt terminal is to be connected to an external earth point (it is not connected to the
thermostat internal earth).
The thermostat 110Vdc inputs are reverse polarity protected.
Output connection
There are six M4 stud terminals for output connection: A1, A2, A3, A4, A5 and A6.
The A1 terminal is connected to the "COMMON"' of the five thermostat relays.
Terminals A2, A3 and A4 are connected to external heater contactors, namely: Heater 3 (via
FADSR), Heater 2 and Heater 1 respectively.
Terminal A5 is connected to drive the Lower lever damper solenoid (LLDS).
Terminal A6 is connected to the external Cool contactor.
Supply and outputs Terminal
Terminals
Descriptions
A1 Common supply of output relays,
415Vac or 110Vdc
A2 Heater 3 and Fresh air damper
A3 Heater 2
A4 Heater 1
A5 Lower level damper solenoid
A6 Cooling
0V Supply 0Vdc
110Vdc Supply 110Vdc
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Instruction Manual
Termate M4 stud terminals are used; these have a voltage clearance of 20mm and 25mm
creepage distance and is suitable for 415Vac switching.
Non-metallic fixings are used on the terminal to meet the voltage clearance requirement.
Sensor connection
The saloon sensor, external to the thermostat unit, has three wire connections, a screen (green)
and two sensor wires (red and blue). It is supplied with 250mm of screen cable, type BR Cat.
No. 6/146700.
The green wire is to be connected to the M4 stud terminal marked "SCREEN" inside the
thermostat unit; the two sensor wires (red and blue) can to be connected in any order to the
M4 terminal marked "0V" and "SALOON" (the PT100 sensor is a passive resistive device and
has no polarity).
The other sensor, which senses the ambient temperature, is factory fixed inside the thermostat
unit.
Sensor terminal
Terminals Descriptions
SALOON Saloon air sensor (to be connected)
0V Supply 0Vdc terminal
SCREEN Sensor screens
A 3-way Termate M4 stud terminals are used for the connections of the saloon sensor.
Diagnostic Test socket
Terminals Descriptions
SALOON Saloon air sensor
0V Common returns from sensor and supply
20Vdc Supply to TC1005 test equipment
A 5-way Litton rear-panel mounted receptacle is fitted to the thermostat unit.
Test and calibration
The 505MST/M thermostat units can be tested and calibrated on site with a dedicated Test
and Calibration unit, model TC1000.
The TC1000 unit consists of a LCD display, a 10-turns potentiometer and one switch.
Connection of the unit to the system is made via a 5-way connector. The TC1000 comes with
its own carrying case.
The TC1000 unit's LCD display two different temperatures: the saloon sensor temperature and
the saloon simulated test temperature.
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Powtier Controls Limited 505MST Thermostat
Instruction Manual
System layout diagram
All Rights Reserved.
C
Filename:
Size:
Drawing No.: Title:
Tactical Controls Limited
Rev. Description Iss. Ch . Auth. Date
A2
LAYOUT
135.0
ALL DIMENSIONS IN MM.
MATERIAL: SHEET STEEL 16SWG FINISH: GREY HAMMER POWDER COAT
12.0
WEIGHT 2.6 KG
Ø20.0
250.0
220.0
Ø26.0 25.0
M6 STUD
10.0
55.0
7.5
230.0
M6 Fixing
Hole
CHAIN 25.0
DIAGNOSTIC SOCKET
20.0
505MST\DWG\LAYOUT
16 JUNE 1998
505MST LAYOUT DIAGRAM
PRODUCTION DRAWING4.0
DUST CAP
57.5
30.0
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Powtier Controls Limited 505MST Thermostat
Instruction Manual
System connection diagram
ALL DIMENSIONS ARE IN MM. GENERAL TOLERANCE X = +/-0.5 X.X = +/-0.05
All Rights Reserved.
C
Filename:
Size:
Drawing No.: Title:
Tactical Controls Limited
Rev. Description Iss. Ch . Auth. Date
A3
0 110
SALOON
SCREEN
BR CAT.NO. 6/146/700
A6 A5 A4 A3 A2 A1
COOL LLDS 8KW 16KW 24KW
HEATER 3HEATER 2HEATER 1 COM
505MST CONNECTION DIAGRAM
505MST\DWG\CONNECT
CONNECT
5-JUN-19981.0 PRODUCTION ISSUE
0V 110VDC
AMBIENT
SENSOR
BLUE
CABLE TYPE
SALOON SENSOR
GREEN
RED
EARTH
MULTI-STAGE
THERMOSTAT
505MST
0V
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