technical background information

A word on EMC

EMC (electro magnetic compatibility) is an important factor for electrical and electronic equipement. Dedicated  norms determine in what extend equipment may cause electro magnetic radiation and how much they may be influenced by external radiation themselves;  radiation and immunity. 

EMC problems cause major disruptions with huge financial damages every year. The authorities have announced that from July 20, 2009 the responsibility for EMC damages will be with the owner of the equipment. On the web site of the Dutch authorities (NEN) you will find more information in Dutch. LINK

EMC is often not well understood and many will fall back to the existing norms. However, these norms give a certain amount of free interpretation which is gladly used by many manufacturors, making there products compliant to the norm, but hardly suitable for the application they were build for.

How come ? The norm for radiation (EN-55022) has 2 classifications:Class A and Class B.

Class A was meant for industrial en commercial use. The authorities assume that in these environments all equipment is protected against radiation anyway so they have lowered their standards. In contrast with what you may think, the industrial grade Class A has lower specs than the domestic grade Class B. This explains why you will find stickers on your equipment that states that you may need to take additional measures to assure that their product will not cause radio interference...

Protection in a PDU

Protection in a PDU can serve 2 purposes:

  • protection against overload
  • to isolate errors

In case of protection against overload: in some cases we need to install breakers to comply with legislation. An outlet with In = 16 A (such as a Schuko) must be protected with a 16 A breaker. When the PDU is connected to a 32 A feed, it is mandatory to have a protection device on the PDU. A breaker is normally sufficient for this purpose, since it offers the required protection, it is easy to use (resettable) and cheap.

It becomes more complex when you want to isolate an error. The intention is that a protection device close to the error reacts more quickly than a device upstream. This way an error has no effect on other equipment than those behind the protection device in the PDU. To achieve this, you need to take a whole list of technical details into consideration before you can decide what protection device is most appropriate. We have tried to explain some of these details in a white paper that can be found in our download area (link). 

Schleifenbauer makes use of special fuse holders (revolver model) that have the same size as MCBs. Fuses normally act more quickly than MCBs and have a guaranteed selectivity (min. 1.6) that ensure a predictable response under any circumstances. The negative side of fuses is that you need to adhere to a logistics mechanism that ensures someone has 24-hour access to the right fuses when a fuse is blown.

We can also implement MCBs into our profile so you have all the options to choose the right protection device for your purpose.

Download our white paper here.

What is the advantage of a bi-stable relay?

Schleifenbauer uses bi-stable relays in its PDUs with switched outlets. We thereby take a significant lead on (most of) our competitors, but what is so special about these relays?

A 'classic' relay in a PDU has a default position and that is OFF. This option is taken to ensure that after a power outage, when switching the power back on, not all the relays are switched ON. This could result in a cycle voltage that is too great for the preceding fuses, due to which everything goes off again immediately after the power is restored. These 'default off' relays can be switched on by allowing low voltage through, with which a magnetic connection is closed and the relay switches ON. This means that a relay that is permanently ON consumes about 1 Watt of power (and converts it into heat). In a PDU with 24 outlets, this can mean 24 Watts on top of the output of the power supply and the metering electronics. These are considerable losses during the lifetime of the device. Another disadvantage of these relays is that when there is a breakdown in the power supply (without the main power being interrupted), all the relays are switched OFF.

A bi-stable relay is, as the name implies, stable in both the ON and OFF positions. Power is only needed to switch from one position to the other. If there is no switching, then the relay uses 0 Watts. To ensure that the relay is switched off in the event of a power outage, electronics have been added which, when the main power is interrupted, switches the relay OFF. After the main power is restored, dependent on the setting of the PDU, the relay is switched back ON. In the event of a breakdown in the power supply to the relay, the relays remain in their current position. Switching is no longer possible it is true, but the power to the equipment remains assured if the relay was ON during the breakdown.

What syslog messages are possible ?

NOTICE

4

SYSTEM

booted successfully

NOTICE

6

EVENT

reset button pressed

NOTICE

11

PDU

changing address of PDU (from)

NOTICE

12

PDU

changing address of PDU (to)

NOTICE

13

PDU

renumbering all PDUs

NOTICE

14

PDU

initialising zero addresses

NOTICE

15

PDU

performing firmware upgrade

NOTICE

16

PDU

rebooting every PDU

NOTICE

17

PDU

reset all alerts

NOTICE

18

ALERT

pdu online again

NOTICE

19

SYSTEM

GW firmware upgrade

NOTICE

22

MYSQL

starts upload session

NOTICE

26

YUSTON

starts upload session

NOTICE

27

YUSTON

new encryption key received

NOTICE

28

PDU

reset alerts command received

NOTICE

29

PDU

reset input kWh counter command received

NOTICE

30

PDU

reset output kWh counter command received

NOTICE

31

PDU

reset peak values command received

NOTICE

39

RING

scanning bus

NOTICE

40

RING

ring is closed

NOTICE

47

PDU

switch outlet on

NOTICE

48

PDU

switch outlet off

NOTICE

63

NTP

time set

NOTICE

70

MYSQL

starting status update

NOTICE

71

MYSQL

finished status update

NOTICE

72

MYSQL

starting config update

NOTICE

73

MYSQL

finished config update

NOTICE

74

MYSQL

starting outlet update

NOTICE

75

MYSQL

finished outlet update

NOTICE

76

MYSQL

starting measurement update

NOTICE

77

MYSQL

finished measurement update

WARNING

96

SYSTEM

hard reset

WARNING

97

SYSTEM

switch to DHCP mode

WARNING

98

SYSTEM

soft reset

WARNING

99

SYSTEM

switch to Static IP

WARNING

101

FLASH

flash erased

WARNING

102

SYSTEM

user requested reboot

WARNING

103

FLASH

version upgraded

WARNING

128

RING

ring is broken in one direction (close ring not receiving)

WARNING

129

RING

ring is broken in one direction (data bus not receiving)

WARNING

130

RING

ring is broken in both directions

WARNING

134

PDU

outdated firmware

WARNING

142

ALERT

A PDU raised a new alert

WARNING

143

ALERT

All alerts cleared

WARNING

144

ALERT

pdu internal error

WARNING

145

ALERT

temperature

WARNING

146

ALERT

input current treshold

WARNING

147

ALERT

output current treshold

WARNING

148

ALERT

input voltage treshold

WARNING

149

ALERT

sudden current drop detected

WARNING

150

ALERT

pdu offline

ERROR

160

NETWORK

write error

ERROR

161

NETWORK

fatal comm error (reboot)

ERROR

162

NETWORK

read error

ERROR

163

NETWORK

no hardware address for this interface (reboot)

ERROR

164

NETWORK

receive timeout

ERROR

165

NETWORK

link gone down

ERROR

166

NETWORK

socket not established

ERROR

167

NETWORK

hostname could not be resolved

ERROR

168

NETWORK

could not resolve remote hardware port

ERROR

170

NETWORK

socket initialization failed

ERROR

172

NETWORK

interface down

ERROR

173

NETWORK

no dhcp ip address received

ERROR

174

NETWORK

link down

ERROR

176

MISC

bad parameter for led out

ERROR

177

NTP

server unreachable

ERROR

178

NTP

server unreliable

ERROR

179

NTP

connection timed out

ERROR

180

NTP

unknown socket error

ERROR

181

NTP

incomplete answer

ERROR

192

SOCKET

wrong tag

ERROR

193

SOCKET

data  too long

ERROR

194

SOCKET

wrong checksum

ERROR

195

SOCKET

wrong check bytes

ERROR

196

SOCKET

illegal command

ERROR

197

SOCKET

data bus receive error

ERROR

208

YUSTON

invalid header tag (not BLOB)

ERROR

209

YUSTON

waiting for key...

ERROR

210

YUSTON

unsupported (major) version

ERROR

211

YUSTON

comm error, no ack received

ERROR

212

YUSTON

invalid field length

ERROR

213

YUSTON

unknown field type [field type]

ERROR

214

YUSTON

blob corrupt

ERROR

216

YUSTON

header checksum error

ERROR

218

YUSTON

data block checksum error

ERROR

220

YUSTON

data block field length error

ERROR

222

YUSTON

data block corrupt

ERROR

224

MYSQL

cannot open tcp connection

ERROR

225

MYSQL

cannot open socket

ERROR

226

MYSQL

no answer from server on connect

ERROR

227

MYSQL

wrong protocol, must be 10

ERROR

228

MYSQL

authentication error

ERROR

229

MYSQL

old style password, upgrade first

ERROR

240

FLASH

invalid user block, possibly corrupted system id block

ERROR

242

FLASH

parameters (re-) initialized to default values

ERROR

244

FLASH

error while writing parameters 

ERROR

246

FLASH

checksum error 

ERROR

250

SYSTEM

memory allocation error